Screening media for vibratory separators

Abstract

Screening media to screen oversized material includes a main body and a plurality of openings extending through the main body between an upward facing contact face and a downward facing bottom face. A textured pattern is provided at the contact face to provide a roughened surface for the partial entrapment of material fines. Such a configuration protects the screen media from aggressive contact with the material to be screened and provides a bedding layer that is maintained by material-on-material attrition during bulk material flow over the media.

Claims

1. A screening media arranged to screen material, the media comprising: a main body having a contact face of a top layer arranged to be upward facing to contact material to be screened and a bottom face of a second layer arranged to be downward facing, wherein a repeating textured pattern is provided along the top layer, the main body having a thickness defined between the contact and bottom faces, wherein the main body includes a top layer material and a second layer material; and a plurality of spaced screening apertures extending through the thickness of the main body between the contact and bottom faces, wherein the top layer material is bonded or attached together with the second layer material to form a composite structure in which the top layer material has one material characteristic and the second layer material has another material characteristic being different from the top layer material characteristic, wherein the second layer material is material reinforced with fabric fibres integrated in the material, wherein a warp and weft of fibres have a same characteristic, wherein strength and durability rendered by the fabric reinforced second layer material generates a dimension tolerance and capacity to the apertures when being punched out of the media, a size of the plurality of apertures being uniform through the thickness of the media such that a cross sectional area of the openings at the contact face is approximately equal to the cross-sectional area of the openings at the bottom face.

2. The media as claimed in claim 1, wherein the top layer material is vulcanized rubber and the second layer material is vulcanized rubber and reinforced fabric.

3. The media as claimed in claim 1, wherein the second layer is reinforced with fabric selected from the group consisting of polyesters, polyamides, nylon and carbon fibres.

4. The media as claimed in claim 1, wherein the second layer is reinforced with fabric having more than one layer.

5. The media as claimed in claim 1, wherein the second layer which is reinforced with fabric, has a color different from a color of the top layer.

6. The media as claimed in claim 1, wherein a shape of said screening apertures is selected from the group consisting of a quadrangle, circle, oval and triangle.

7. The media as claimed in claim 1, wherein the top layer is adhered to the second layer by a primer.

8. The media as claimed in claim 1, wherein said screening media is cross-tensioned between a pair of sidewalls perpendicular to a direction of a movement of material being screened.

9. The media as claimed in claim 1, wherein said screening media is longitudinally tensioned between a plurality of tensioning devices in a same direction as of a movement of material being screened.

10. A screening apparatus arranged to screen bulk material, the apparatus comprising: a support frame; a plurality of support beams; at least one pair of sidewalls; a plurality of clamp bars; a plurality of tensioning devices; and a screening media as claimed in claim 1 mounted on the plurality of support beams and extended between the sidewalls, wherein said screening media is cross-tensioned between the respective sidewalls perpendicular to a direction of a movement of material being screened.

11. A screening apparatus arranged to screen bulk material, the apparatus comprising: a support frame; a plurality of support beams; at least one pair of sidewalls; a plurality of clamp bars; a plurality of tensioning devices; and a screening media as claimed in claim 1 mounted on the plurality of support beams and extended between the sidewalls, wherein said screening media is longitudinally tensioned between of respective tensioning devices in a same direction as that of a movement of material being screened.

12. A method of fabrication of a screening media comprising the steps of: providing a screening media, the screening media including a main body having a contact face of a top layer arranged to be upward facing to contact material to be screened and a bottom face of a second layer arranged to be downward facing, the main body having a thickness defined between the contact and bottom faces, wherein the main body includes a top layer material and a second layer material, wherein the top layer material is vulcanized rubber and the second layer material is vulcanized rubber and reinforced fabric punching the screening media to create a plurality of spaced screening apertures extending through the thickness of the main body between the contact and bottom faces and providing a repeating textured pattern provided along the top layer, wherein the top layer material is bonded or attached together with the second layer material to form a composite structure in which the top layer material has one material characteristic and the second layer material has another material characteristic being different from the top layer material characteristic, wherein the second layer material is material reinforced with fabric fibres integrated in the material, wherein a warp and weft of fibres have a same characteristic, wherein strength and durability rendered by the fabric reinforced second layer material generates a dimension tolerance and capacity to the apertures when being punched out of the media, a size of the plurality of apertures being uniform through the thickness of the media such that a cross sectional area of the openings at the contact face is approximately equal to the cross-sectional area of the openings at the bottom face; providing an apparatus including a support frame, a plurality of support beams, at least one pair of sidewalls, a plurality of clamp bars, and a plurality of tensioning devices; mounting the screening media on the plurality of support beams and extending between the sidewalls, wherein the screening media is cross-tensioned or longitudinally tensioned between the sidewalls; and cutting the screening media into screen mats according to a size of the screening apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will now be explained in relation to the accompanying drawings in which,

(2) FIG. 1 illustrates the top view of the screen assembly according to one of the preferred embodiments of the present disclosure;

(3) FIG. 2 illustrates the perspective view of the screen assembly according to one of the preferred embodiments of the present disclosure

(4) FIG. 3 illustrates the enlarged side view of the screen assembly showing screening media clamped to the screening apparatus using a tensioning device according to one of the preferred embodiments of the present disclosure;

(5) FIG. 4 illustrates the enlarged view of the screening media according to one of the preferred embodiments of the present disclosure;

(6) FIGS. 5A, 5B and 5C illustrate the enlarged view of the cross-section of screening media according to one of the preferred embodiments of the present disclosure

(7) FIG. 6 illustrates the enlarged view of the cross-section of screening media according to one of the preferred embodiments of the present disclosure when the top layer is torn and the reinforced fabric layer is seen as wear indicator.

(8) FIG. 7A illustrates a magnified view of the contact face of the screening media having a textured pattern formed by peaks and troughs according to a specific implementation of the present invention and 7B shows a side elevation end view of the textured pattern at the contact face of FIG. 7A.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) The present disclosure will now be described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

(10) The present disclosure provides a solution to the above stated problems in presently used woven wire-mesh screens by envisaging a screening media to screen material, the media comprising:

(11) a main body having a contact face intended to be upward facing to be in contact with the material to be screened and a bottom face intended to be downward facing, the main body having a thickness defined between the contact and bottom faces made with first layer material and a second layer material. This main body has a plurality of openings extending through the thickness of the main body between the contact and bottom faces.

(12) The first layer material may be bonded or attached together with the second layer material to form a composite structure. The first layer may have a textured pattern on the surface to prevent wear and tear, according to one of the embodiments of the present disclosure. The second layer is preferably reinforced with fabric which in addition to strengthening the screening media, also acts as a wear-indicator owing to the color of the fabric which gets exposed when the top layer gets torn, according to one of the embodiments of the present disclosure.

(13) Referring to FIGS. 1 and 2, the top and perspective view of the screen assembly are illustrated respectively. The screening media 1 is secured over the support frame 2 with the help of support beam 3. The screening media 1 can be stretched across the support frame 2 in cross-tensioned or longitudinally tensioned fashion between a pair of side walls 4. Media 1 is supported at its underside by a plurality of lengthwise extending support beams 3 and clamped on to the sidewalls 4 by clamp bars 6. The screening media 1 is held down at the centre of the screen assembly to tighten and stretch it optimally. The screen assembly also uses rubber capping 5 to prevent the screen media from wear.

(14) Referring to FIG. 3, the enlarged side view of the screen assembly is seen, where the screening media 1 is shown to be clamped to the side wall 4 with the help of a tensioning device 7. The tensioning device 7 seen in the figure, are made of aluminium according to one of the embodiments of the present disclosure. These tensioning devices 7 are structured based on the method of tensioning. They may be designed differently for cross-tensioned and longitudinally tensioned screen cloths. The screening media 1 is held down at the centre of the screen assembly to tighten and stretch it optimally. The screen assembly also uses rubber capping 5 to prevent the screen media from wear.

(15) Referring to FIG. 4, a section of the screening media mat is enlarged and shown. It is visible from the figure that a plurality of screening apertures 9 extend through the thickness of the media. The screening apertures 9 punched into the screening media may be of any shape. The preferred shape for fine screening application is square. These squares may be punched in-line or staggered against each other. The dimension, shape and orientation of the punched screening apertures 9 depend on the application and the particle size of the material which is to be screened. According to one of the embodiments of the present disclosure the screening media 1 has rectangular screening apertures 9 punched into it. The alignment of the screening apertures 9 is chosen on the basis of the requirement of the screening operation.

(16) Referring to FIGS. 5A, 5B and 5C, the cross-sectional view of the screening media 1 illustrates the layers constituting the screening media 1. According to one of the preferred embodiments of the disclosure, the screening media 1 comprises of at least one layer of rubber 8 over at least one layer of fabric-reinforced rubber 10. These two layers are clearly visible in FIG. 5A. In FIG. 5B, two layers 10 and 11, can be seen below the top layer 8. Similarly FIG. 5C shows three layers 10, 11 and 12 below the top layer 8. The more the number of layers, more is the reinforcement and more is the strength of the screening media. The fabric used for reinforcement may be selected from a range of polyesters, polyamides, nylon or carbon fibres. The reinforcement of fiber must have the same characteristics of both warp and weft, that is the same e-module. The top layer 8 is preferably made using rubber or polyurethane materials. Some examples of commonly used rubber grades are SR, NBR and BR. For applications inducing high wear and tear, it is recommended that the rubber used for screening media 1 has the hardness in the range of 40 to 70 shore A. The second layer 10 is rubber reinforced with fabric to add strength to the screening media 1. To reinforce, the fibres of the fabric are integrated in the rubber or polymeric material at the time of extrusion. Reinforcement of the screening media 1 allows the screen assembly to take bigger load without yielding, and thus allows for decrease in the thickness of the screening media 1 making it lighter and easier to transport than its wire-mesh counterparts. Post-reinforcement, it is also possible to decrease the amount of material between the openings of the screening media 1, thereby increasing the total open area of the screening media 1. Therefore, reinforcement of screening media 1 results in its increased efficiency and dimensional stability.

(17) Further observed in the FIG. 6, is that the top layer 8 is torn due to wear and tear. The torn top layer 8 exposes the fabric-reinforced rubber layer 10 beneath it. Since the layer 10 is differently colored than the top rubber layer 8, it works like a wear-indicator to forewarn the operator about the wear and tear of the screen, so that it can be replaced before greater damage is caused. The torn portion 13 is indicative of the wear.

(18) Referring to FIGS. 7A and 7B, the textured pattern on the surface of the screening media 1 can be observed. According to the specific implementation, the textured pattern extends over the entire surface of the top layer. The textured pattern is formed from peaks 14 and respective troughs 15 that collectively define a repeating pattern. The textured pattern may be created conveniently by pressing a woven mesh (or other substrate) into the first layer 8 (when formed from a rubber material) as part of the vulcanisation process. Once the mesh is removed, an imprinted pattern is formed corresponding to the shape profile of the woven mesh so as to define the peaks 14 and troughs 15. The shape of the textured pattern at the surface of the top layer 8 may be achieved by selecting the appropriate dimensions and cross sectional shape profile of the warps and wefts of the imprinting mesh. According to the specific implementation, the textured pattern at the surface of the top layer is formed by troughs 15 that are continuously curved which are in turn formed by the wefts and warps having a generally circular cross sectional profile.

(19) The relative depth of the textured pattern (defined as the separation distance between the peaks 14 and troughs 15 in a plane perpendicular to the plane of the media 11) is much less than the total thickness of the media 1 and the thickness of the top layer 8. Such a configuration provides a surface roughness whilst ensuring that the top layer 8 comprises sufficient thickness to achieve the desired structural strength of the media 1 capable of being pre-tensioned between sidewalls 4. In particular, the depth of the trough 15 may extend in a range 5% to 50% of thickness of the top layer 8.

(20) The rubber for the screening media is manufactured using an automatic mat vulcanizing system (AUMA) which involves the use of a slow-rotating steam-heated drum under controlled pressure conditions. The rubber media thus produced is reinforced with a polyester or a polyamide fabric which has a color different from the color of the rubber. The reinforced media is then punched into, to make screening apertures of desired shape. Thereafter, it is cut into pieces of desired length as per the requirement. The screening media thus prepared, is then installed on the cambered screen decks of the screening unit. The screen decks are cambered to prevent the screening media from flapping during the operation which can lead to breaking of the screening media. The screening media is secured over the tensioning device using clamp bars and tensioning devices for example made of aluminium, either in a cross-tensioned or longitudinally tensioned fashion. There is capping of rubber provided under the screening media to protect it from wearing.

(21) The present disclosure offers a host of advantages over its wire-mesh predecessors. The tensioned rubber media reinforced with fabric is stronger and more durable and therefore requires fewer media changes resulting in lower screen downtime. This screening media also has better hole tolerance, and increased capacity since owing to better durability, it allows more holes to be punched into it. It is free from the problems of blinding and pegging which are frequently encountered in woven wire-mesh screens. Hence, it provides better sizing accuracy even for fine particles (close to 2 mm particle diameter). There is almost no oversize or fines contamination in the screened product and consistent particle size range is maintained during the course of operation of the screen. As the screening media is durable and less prone to wear and blinding, there are fewer operational stops for inspection and troubleshooting. The media needs to be replaced much less frequently as compared to the woven wire-mesh screens. Along with the functional advantages, the screening media also offers benefits of easy and quick installation, and cost-effective production, thus ensuring long-term media economy. The screening media 1 is smooth, light and flexible and can be conveniently stored and transported in the form of a roll providing the user with the advantage of greatly simplified handling. It has no sharp edges like woven wire mesh and is therefore not hazardous for the operator carrying and installing the screening media. Since it is made of rubber, it does not make as much noise as metallic wire-mesh during the vibratory operations. The textured pattern on the surface of the top layer 8 provides the desired wear-resistance to the screening media 1.

(22) In addition to these advantages, the tensioned rubber screening media 1 with reinforced fabric layer of a color different from the top rubber layer, offers the novel feature of wear-indication to the operator. If the top layer gets worn due to excessive usage, the layer beneath it starts showing and is easily observed by the operator since it is of a different, preferably contrasting colour. At this indication, the operator can replace the screening media before any more losses are incurred due to screen breakage.

(23) The present disclosure has a wide range of applications in the industry. It is an all-round screening media designed primarily for final and intermediate screening in both wet and dry applications including but not limited to mining, mineral processing, construction, metallurgy and recycling industries.