AU2008303436B2 - Annular grinding ring - Google Patents

Abstract

An annular grinding ring (10) is described having a radially outwardly facing peripheral surface (12) and a radially inwardly facing peripheral surface (14), the ring (10) including a plurality of projections (20) each of which extends away from the radially inwardly facing peripheral surface (14) towards an axis (A) of the grinding ring (10).

Description

Annular Grinding Ring Technical Field 5 This invention relates to an annular grinding ring, particularly, but not exclusively for use in a grinding mill for grinding/pulverising coal and the like. Background Art One known type of grinding mill includes upper and lower annular grinding 10 rings and a plurality of grinding balls positioned therebetween. In use the lower ring is connected to or fixed relative to a rotatable table. When the table rotates the lower ring is caused to rotate about its axis relative to the upper ring, which in turn causes the grinding balls to move along recesses in the upper and lower grinding rings. Particulate material, e.g. coal, is supplied 15 through a central aperture in the upper grinding ring and migrates outwardly in between the grinding rings and the grinding balls. The particulate material is crushed/pulverised between adjacent grinding balls and/or between the grinding balls and the upper or lower grinding rings. 20 When assembling a grinding mill it is generally necessary to lower the grinding rings and grinding balls into a relatively deep recess in a main body of the grinding mill. Lowering of these component parts into the recess is typically undertaken by connecting the component parts to a crane or hoist, so that the component can lowered into the recess safely. In addition, periodically, the 25 grinding mill requires dismantling so that component parts thereof can be serviced, repaired and/or replaced, and thus the component parts need to be lifted out of the recess. In order to assist in lowering component parts into and lifting component part 30 out of the recess, one solution has been to provide on the grinding rings a plurality of recesses spaced around the radially outwardly facing periphery of H11998WO 2280383_2 (GHMattems) P83W&0AU 2 the ring. A hook is then received in each recess so that the ring can be lifted/lowered safely. However, it is often the case that an external diameter of the grinding ring is 5 only slightly smaller that an internal diameter or size of the recess in the main body of the grinding mill. As a result, it is often not possible to use the peripheral recesses in the ring, because the hooks which engage those recesses stand out too proud of the external diameter of the grinding ring. 10 It has been proposed in international patent application publication no. W02007/065214 (Bradken Resources Pty Limited) to provide a plurality of recesses in the radially inwardly facing periphery of the ring. Lifting hooks engage these recesses and thus do not potentially come into contact with an internal surface of the recess in the main body of the grinding mill. 15 However, the configuration shown in W02007/065214 has disadvantages. As can be seen from figures 2 and 3 of W02007/065214, when the lower grinding ring (referenced as 100 in the patent drawings) has been lowered onto a yoke table (2), it is not possible for the hooks (22) to be removed from their 20 respective recesses (20) because of the positioning of the yoke table (2) and the yoke plate (5). This means that the hooks (22) must remain in situ whilst the grinding mill is in use. Leaving the hooks (22) in situ can have detrimental effects on the efficiency of 25 the grinding mill. It is entirely possible for the hooks to become damaged during the grinding process due to the large crushed forces created, which could result in the hooks (22) not being useable when it is desired to lift the lower ring out of the recess in the main body of the grinding mill. In addition, plugs which W02007/065214 proposes are to be inserted into the recess (23) 30 in each hook (22) could easily be dislodged during use, or a user may forget to H1 1998WO 22e0383..2 (GHMstter3) P83966 AU 3 insert them. If the plugs are dislodged or not inserted, the recesses (23) would eventually become clogged with particulate material. This would render the hooks inoperable, which would result in it being very difficult to lift the grinding ring. 5 Furthermore, providing recesses in the inner periphery of the grinding ring can affect the structural integrity of the grinding ring due to a decrease in cross sectional area of the grinding ring at each recess. 10 The above references to the background art do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the method and system as disclosed herein. 15 Summary According to a first aspect of the invention an annular grinding ring is provided having a radially outwardly facing peripheral surface and a radially inwardly facing peripheral surface, the ring including a plurality of projections each of 20 which extends away from the radially inwardly facing peripheral surface towards an axis of the grinding ring. In some embodiments, a lower surface of each projection includes a recess to receive a part of a lifting member. 25 In some embodiments, the projections are spaced substantially evenly from each other around the radially inwardly facing peripheral surface. In some embodiments, three projections are included spaced at 120* from 30 each other about the axis of the grinding ring. H1 1998WO 2260383.2 (GMeMr) P83960AU 4 In some embodiments, four projections are included spaced at 90* from each other about the axis of the grinding ring. 5 In some embodiments, the projections are integral parts of the ring. In some embodiments, the annular grinding ring is cast. In some embodiments, the annular grinding ring is forged. 10 In some embodiments, the annular grinding ring is a lower grinding ring for a grinding mill. According to a second aspect of the invention we provide a grinding mill 15 including an annular grinding ring according to the first aspect of the invention. According to a third aspect of the invention we provide a kit of parts for constructing a grinding mill, including one or more grinding rings each in accordance with the first aspect of the invention. 20 Brief Description of the Drawings Non-limiting embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, of which: 25 Figure 1 is a perspective view of an annular grinding ring in accordance with the present invention; Figure 2 is a cross-sectional view of a part of the grinding ring of figure 1; and 30 H11998Wo 2260383_2 (GHMatters) P83988AU 5 Figure 3 is a perspective view of an underside of the grinding ring of figure 1. Detailed Description of the Drawings 5 Referring to figure 1 there is shown an annular grinding ring 10, which is cast from a suitable iron-based alloy. For example, a high chrome abrasion resistant alloy or a Nickel-Chrome abrasive resistant alloy could be used. Of course, it should be appreciated that any appropriate material could be used. The ring could, of course, be manufactured by forging or any other appropriate 10 manufacturing technique. The ring 10 is a component part of a grinding mill (not shown). The ring 10 in this example is a lower grinding ring, which means that it supports a plurality of spherical grinding members and an upper grinding ring. In use, the ring 10 is 15 supported in a recess in a main body of a grinding mill and is caused to rotate about its axis A. Particulate material, e.g. coal, is forced to flow in between the spherical balls and the upper and lower grinding rings so as to crush/pulverise the material between adjacent grinding balls and/or between the grinding balls and the upper or lower grinding rings. 20 In more detail, the ring 10 has a radially outwardly facing peripheral surface 12 and a radially inwardly facing peripheral surface 14. The peripheral surfaces 12, 14 are joined by upper 16 and lower 18 surfaces. The upper 16 and lower 18 surfaces are substantially parallel with each other, although the upper 25 surface 16 has a recess or channel to receive a plurality of spherical grinding members (not shown). The outer peripheral surface 12 is substantially flat and is substantially parallel with the axis A of the ring 10. The inner peripheral surface 14 is inclined relative to the axis A such that its connection to the lower surface 18 is spaced farther away from the axis A than its connection to the 30 upper surface 16. H1 1998WO 2260383_2 (GHMatters) P83986.AU 6 The ring 10 also includes four projections 20, each of which is connected to the radially inwardly facing peripheral surface 14. The four projections 20 are spaced at 900 from each other about the axis A of the ring 10. In this example, 5 the projections 20 are integral parts of the cast ring 10, although it must be appreciated that the projections 20 could be separately formed and mechanically or otherwise connected to the radially inwardly facing peripheral surface 14 of the ring 10. In addition, it will be appreciated that two or more projections 20 could be used, for example three projections spaced at 1200 10 from each other about the axis A of the ring 10 or six projections spaced at 60* from each other about the axis A of the ring 10. Each projection 20 extends away from the radially inwardly facing peripheral surface 14 generally radially towards the axis A of the ring 10. A lower surface 15 of each projection 20 includes a recess 22 to receive a part of a lifting member 32 (discussed later). In order to lift the ring 20 from a surface, a lifting device 30 (see figure 1) is used. The device 30 includes two substantially parallel frame members 33 20 which are connected to each other by four spaced substantially parallel frame member 31. The frame members 31 are grouped in pairs with one pair positioned towards one end of the frame members 33 and the other pair positioned towards the opposite end of the frame members 33, and extend generally perpendicular to the frame members 33. The lifting device 30 also 25 includes four lifting members 32, which in this example are flexible loops of a suitable material which is strong enough to support the weight of the ring 10. One frame member 31 of each pair of frame members 31 supports at each end thereof a flexible loop 32. The device 30 is connectable to a crane or the like. 30 H11998WO 2260363_.2 (GHMatlers) P839M.AU 7 The flexible loops 32 are each engaged with a respective projection 20, so that a part of the loop engages the recess 22. The lifting device 30 is then raised, which in turn raises the ring 10 from the surface. The ring 10 is then lowered into a recess in a main body of the grinding mill (not shown). Once the ring 10 5 has been lowered into place, i.e. onto a rotateable table, the loops 32 are disengaged from the projections 20 and the lifting device 30 is lifted out of the recess in the main body of the grinding mill. Providing a plurality of projections 20 on the radially inwardly facing peripheral 10 surface 14 of the grinding ring 10 is advantageous over known proposals, and results in much simpler lifting and lowering of the ring 10 into and out of the recess in the main body of the grinding mill. There is also no requirement to leave in situ any lifting hooks or the like. Furthermore, the structural integrity of the ring is not compromised, because the cross-sectional area of the ring at 15 the position of each projection is not decreased. In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used 20 in an inclusive sense, i.e., to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the method and apparatus. H1 1998WO 22803832 (GHMatters) P8398 AU

Claims (12)

1. An annular grinding ring having a radially outwardly facing peripheral surface and a radially inwardly facing peripheral surface, the ring including a 5 plurality of projections each of which extends away from the radially inwardly facing peripheral surface towards an axis of the grinding ring.

2. An annular grinding ring according to claim 1 wherein a lower surface of each projection includes a recess to receive a part of a lifting member. 10

3. An annular grinding ring according to claim 1 or claim 2 wherein the projections are spaced substantially evenly from each other around the radially inwardly facing peripheral surface. 15

4. An annular grinding ring according to any preceding claim including three projections spaced at 1200 from each other about the axis of the grinding ring.

5. An annular grinding ring according to any preceding claim including four 20 projections spaced at 90* from each other about the axis of the grinding ring.

6. An annular grinding ring according to any preceding claim wherein the projections are integral parts of the ring. 25

7. An annular grinding ring according to any preceding claim which is cast.

8. An annular grinding ring according to any preceding claim which is forged. H11998WO 2260303_2 (GHMattem) P839W.AU 9

9. An annular grinding ring according to any preceding claim which is a lower grinding ring for a grinding mill.

10. A grinding mill including an annular grinding ring according to any 5 preceding claim.

11. A kit of parts for constructing a grinding mill, including one or more grinding rings each in accordance with the grinding ring of any one of claims 1 to 9. 10

12. An annular grinding ring substantially as hereinbefore described with reference to and/or as shown in the accompanying drawings. H1 1998WO 2260383_2 (GHMatter) P839W8.AU