AU2007201396B2 - Ore Screening Panel - Google Patents

Description

AUSTRALIA Patents Act ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Application Number: 20072 Lodgement Date: 2 nd April 2007 Nominated Patentee: Screenex Australia Pty Ltd Invention Title: Ore Screening Panel The following statement is a full description of this invention, including the best method of performing it known to the applicant.

Ore Screening Panel 5 This invention relates to improvements in ore screening panels used in the separation and grading of materials in the mining and quarrying industries. Background to the invention Australian patent 482212 proposed a modular screening panel system for ore 1o screening decks which is now widely used by the mining industry and replaced the earlier screening cloths, and large wire screening frames. The screening panels were all of the same size [eg. 300mm] and made of reinforced polyurethane. The panels are adapted to be secured to an underlying support frame using dependent spigots which are a force fit into 15 corresponding apertures in the support frame. Patent 517319 provided an alternative method of securing the panels to the frame using a pin expanded fastening concept. A difficulty encountered in using these panels is that the screening apertures can become clogged with material failing to pass through the apertures. 20 When a portion of a screen deck is affected in this way it is said to be blinded and a blinded screen is less efficient because of the reduction in open area. Blinding of screening panels is most prevalent in dry screening where there is no water to wash out the apertures and where the aperture size is below 10mm. Problems are encountered also in dry screening where the water 25 content of the ore is high enough to encourage agglomeration of ore fines. Patent 538559 attempted to address this problem by making the ribs which define individual screen apertures of different flexural strengths by varying the cross sectional dimensions or internal reinforcements. Patent 608392 also sought to overcome this problem by providing greater 30 flexibility to the periphery of each aperture. This was achieved by providing zig-zag ribs extending across the panel to define screening apertures between the ribs. The self cleaning action is thus dependent on the shape and arrangement of the apertures in the screening surface. Patent 712862 provided an ore screening panel for fine screening wherein the 35 screening surface has apertures formed between aperture ribs, said aperture 2 ribs having projections on their opposed edges to define apertures between said projections which are capable screening material of a size below 2mm. Patent 731011 sought to prevent blinding by providing a flexible ore screening panel adapted for mounting on a screening deck, which includes a 5 screening surface integrally formed on a reinforcing frame part of which lies below said screening surface, wherein the screening surface is only attached to the frame at its periphery. This arrangement has been successful but the provision of a support frame across the screening surface and the arrangement of apertures does inhibit the efficiency of screening . io Patent 772638 discloses a panel composed of polymeric material having a shore hardness greater than 20 which includes a screening surface having hexagonal apertures arranged in the surface in staggered formation so that the ribs which define the apertures are regular in width and the aperture width to rib width ratio is 0.8:1 to 2.8: 1 and the rib width to rib thickness ratio is 15 1:0.8 to 1:2. It is an object of this invention to provide a self cleaning panel with throughput and screening efficiency for a range of aperture sizes. Brief description of the invention 20 To this end the present invention provides an ore screening panel adapted for mounting on a screening deck, composed of a hard elastomeric material which includes a peripheral frame in which reinforcing is incorporated in the peripheral frame members; a screening surface extending between the peripheral frame members; said screening surface having spaced apart ribs 25 extending between one pair of opposed peripheral frame members said ribs having projections on their opposed edges and the projections on adjacent ribs being staggered to define apertures between the staggered projections and the opposed ribs; wherein the projections have stems and heads to define hexagonal apertures. 30 The panel is cast, injection moulded or vulcanised elastomeric material, preferably polyurethane or rubber, which has embedded within it reinforcing bars which define the outer edges of the panel to provide support to the 3 screening surface. The reinforcing can be of plastic or metal. Steel has conventionally been used, but fibre reinforced plastics are preferred because of their lighter weight and resistance to corrosion. The apertures are preferably equal sided hexagons. The apertures extend 5 across the surface to the edges of the panel. The size of the apertures may range from 5 to 60mm. The apertures are tapered inwardly so that they are wider at the screening surface. The depth of the apertures which corresponds to the thickness of the screening surface determines the rigidity of the screening surface. Preferably the ratio of aperture width to rib thickness is io from 0.8: 1 to 2.5: 1. The surface is able to flex and vibrate in a manner akin to a screening cloth. The panels function effectively and are self cleaning. The parameters that enable the flexibility of the screen to be varied to suit a particular application are the thickness of the screening surface, the hardness of the elastomeric 15 material and the distance between adjacent hexagonal apertures which is the same as the width of the ribs which form the apertures. This invention is applicable to any modular screening panel including those of the type described in patent specifications 482212, 517319, 644293. The disclosures of these patents are incorporated herein by reference. 20 The method of manufacturing the panels according to this invention is the same as for conventional panels as outlined in the above mentioned patents. Detailed description of the invention A preferred form of the invention will now be described with reference to the 25 drawings in which: Fig. 1 is a plan view of one screening panel in accordance with the invention. The screening panel 10 is apart from the modification proposed by this invention a conventional modular screening panel. It will be made from 30 polyurethane or some other hard wearing plastic or rubber material and have a shore hardness of 20-95 selected to correspond to the type of particulate ore to be screened and the method of moulding. If the panels are made by injection moulding the hardness cannot be lower than 40, but with air casting 4 the hardness can be as low as 20. In screening iron ore, hardness values above 40 are preferred but for screening coal hardness values as low as 20 may be used The panel has 4 frame members 11, 12 13 land 14 forming a screening 5 surface 16. Ribs 15 extend between frame members 11 and 13. Projections 17 extend from each side of the ribs 15 in a staggered arrangement to form equilateral hexagonal apertures 18. The projections 17 are formed as stems with heads and the dimensions determine the size of the apertures. The apertures are joined by narrow channels 19 between the heads of adjacent to opposing projections. It is not essential that the hexagons be equilateral. The hexagonal apertures taper inwardly in cross-section. The depth of the apertures corresponds to the thickness of the screening surface which is the main determinant of the flexibility of the screen surface. The apertures are tapered so that the apertures are wider at the screening surface than at the is underside of the screening surface 16. The peripheral areas 20 have no apertures because the panel fastening lugs are located in these locations. The panel 10 is stiffened by the frame members 11 to 14 . The whole panel is an integral unit. Reinforcing bars may be embedded in the frame members and may be of steel or rigid plastic such as fibre reinforced plastic. 20 The screening surface 16 can be stiffened to counteract its increased flexibility by providing dependent ribs beneath the ribs 15 or by increasing the thickness of the ribs 15. By varying these parameters, an optimum panel can be designed for a particular ore and screen deck loading. The panels made according to this invention may have aperture sizes from 5 to 60mm. 25 From the above it can be seen that the present invention provides an improved self cleaning panel with a high open area and good screening efficiency.

Claims (4)

1. An ore screening panel adapted for mounting on a screening deck, composed of a hard elastomeric material which includes a peripheral 5 frame made of two pairs of opposing frame members in which reinforcing is incorporated in the peripheral frame members; a screening surface extending between the peripheral frame members; said screening surface having spaced apart ribs extending between one pair of opposed peripheral frame members said ribs having o projections on their opposed edges and the projections on adjacent ribs being staggered to define apertures between the staggered projections and the opposed ribs; wherein the projections have stems and heads which define hexagonal apertures. 5

2. An ore screening panel as claimed in claim 1 in which the apertures are equilateral hexagons.

3. An ore screening panel as claimed in claim 1 wherein the aperture width to rib thickness ratio is 0.8:1 to 2.5: 1. .0

4. An ore screening panel as claimed in any one of claims 1 to 3 wherein the apertures are tapered so that the apertures are wider at the screening surface than on the underside of the screening surface. 25