AU2004264994B2

AU2004264994B2 - Discharge cone for grinding mills

Info

Publication number: AU2004264994B2
Application number: AU2004264994A
Authority: AU
Inventors: Craig Faulkner
Original assignee: Bradken Resources Pty Ltd
Current assignee: Bradken Resources Pty Ltd
Priority date: 2003-08-15
Filing date: 2004-08-13
Publication date: 2010-05-20
Anticipated expiration: 2024-08-13
Also published as: AU2004264994A1

Description

WO 2005/016538 PCT/AU2004/001094 DISCHARGE CONE FOR GRINDING MILLS Scope of the Invention The present invention relates to discharge cones 5 for grinding mills. Background to the Invention Operation of a grinding mill typically involves feeding material and water into one end of the mill and 10 discharging the ground product at the other end of the mill. The product is typically discharged througha discharge cone which forms part of a discharge end wall of the grinding mill. The discharge cone typically comprises a number of discharge cone elements arranged around the 15 central axis of the mill. Each discharge cone element typically comprises a body portion and a nose cone. The body portion typically comprises top and bottom plates separated by one or more upright members. The nose cone projects from the body 20 portion towards the centre of the discharge end wall and includes a central vane and a flange, extending from either side of the vane, and formed integrally with the top plate. The discharge cone elements may be constructed 25 entirely of steel. A problem with all-steel discharge cone elements is that they are extremely heavy, which may reduce the amount of material which can be loaded into the grinding mill and thus reduce the throughput of the mill. Furthermore, because the steel discharge cone elements are 30 heavy, they can be difficult to maneuver during installation and/or removal from the mill. In response to the above problem, discharge cone elements have been constructed from a composite of materials. Upright member(s) have been constructed from 35 steel or rubber coated mild steel plate and the remaining components, in particular the top and bottom plates and the nose cone, have been constructed substantially of -2 rubber. Although such composite material discharge cone elements are lighter than all-steel discharge cone elements, they suffer from another problem. Portions of the 5 rubber components have been found to wear out reasonably quickly thus necessitating the entire discharge cone element to be replaced on a more frequent basis. Replacement of the discharge cone elements is extremely costly in terms of both the cost of replacement element and 10 downtime of the grinding mill. Summary of the Invention According to a first aspect of the present invention there is provided a discharge cone for a grinding 15 mill, the discharge cone comprising a plurality of discharge members, each discharge member being formed from a composite of-materials and comprising a body portion and a nose cone, the body portion comprising a top plate and a bottom plate separated by at least one upright member 20 disposed between the top and bottom plates, the entirety of the nose cone being cast from metal, the nose cone projecting from the body portion towards the centre of the discharge cone and integrally formed with a part of the body portion. 25 Preferably, the body portion is formed from a composite of rubber and metal. Preferably, the top and bottom plates are both formed from a composite of rubber and metal. Preferably, the nose cone comprises a central 30 vane and a downwardly curving flange extending from either side of the vane. Preferably, the flange is arranged to form a substantially continuous surface with a bottom surface of the top plate. 35 Preferably, the central vane is integrally formed with one of the at least one uprights. Preferably, one or more of the at least one uprights includes a metal rib extending along the side of the upright (s) corresponding to the direction in which the 2133934 _1 (GHMatLers) 21/12/09 WO 2005/016538 PCT/AU2004/001094 -3 grinding mill, in use rotates, the metal rib arranged, in use to form a continuous surface with the bottom surface of the top plate. Preferably, the top and bottom plates each 5 comprise a metal reinforcing sheet disposed between layers of rubber. Preferably, each of the discharge members further comprises a lifting boss, located on the axis perpendicular to the top and bottom plates, the axis 10 passing through the centre of mass of the discharge member, the lifting boss adapted for use in manoeuvring the discharge member for installation and/or removal from the grinding mill. Preferably, the lifting boss is integrally formed 15 with one of the at least one uprights and projects through the top plate. Alternatively, each of the discharge members further comprises a pair of lifting lugs, located on the top surface of the top plate and positioned either side of 20 the axis which passes through the centre of mass of the discharge member. Preferably, the nose cone further comprises a clamping tongue at the end of the nose cone which projects towards the centre of the discharge cone, the clamping 25 tongue adapted, in use, to allow the discharge member to be fixed in position in the grinding mill. Preferably, the clamping tongue is adapted, in use, to connect each discharge member to a clamping ring. Preferably, the at least one upright is 30 constructed of white iron steel. The at least one upright may have a non-constant radial cross-section. Preferably, the nose cone is constructed of white iron steel. According to a second aspect of the present 35 invention there is provided a discharge member for a grinding mill as defined in the first aspect of the present invention.

WO 2005/016538 PCT/AU2004/001094 -4 Brief Description of the Drawings Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 5 Fig. 1 is a plan view of the discharge end wall of a grinding mill from inside the mill; Fig. 2 is a perspective rear view of two discharge cone members connected to a clamping ring; Fig. 3 is a perspective view from below of the 10 discharge cone members of Fig. 2; Fig. 4 is a top view of the discharge cone members of Fig. 2; Fig. 5 is a perspective view from the side and below of the discharge cone members of Fig. 2, with one of 15 the discharge cone members partially cut away; and Fig. 6 is a perspective front view of the discharge cone members of Fig. 2. Detailed Description of the Drawings 20 Referring firstly to Fig. 1, a grinding mill has a discharge end wall 10, including inner and outer sections. The inner section is a discharge cone which is made up of a number of discharge cone members 11 each attached to a clamping ring 12 located towards the centre 25 of the discharge end wall 10. The discharge end wall 10 of the grinding mill illustrated in Fig. 1 has ten discharge cone members 11. However, this number may vary according to the type of grinding mill. The outer section of the discharge end wall 10 comprises a plurality of 30 cavity channels 13, which surround the discharge cone members 11. In use, material in the grinding mill passes through a screening wall (not shown) before entering the cavity channels 13 at the rim of the discharge end wall 10. As the grinding mill rotates, the material under 35 gravitational and centrifugal force, passes through the cavity channels 13 into the discharge cone members 11 and exits the grinding mill through the centre of the WO 2005/016538 PCT/AU2004/001094 -5 discharge end wall 10. Referring now to Figs. 2 to 6, each discharge cone member 11 has a body portion 19 and a nose cone 24 projecting away from the body portion 19 towards the 5 clamping ring 12, which in use is located at the centre of the discharge end wall 10. In the embodiment shown in Figs. 2 to 6, the nose cone 24 is integrally formed with part of the body portion 19. The entirety of nose cone 24 is cast from metal, for example steel, and the body 10 portion 19 is constructed of a composite of materials, namely metal and rubber. The body portion 19 has a top plate 20 and a bottom plate 21, spaced apart by a first upright 22 and a second upright 23. The discharge cone member 11 may have 15 only one upright, or alternatively, may have two or more uprights. The top and bottom plates 20 and 21 are shaped as annular segments-and are of approximately the same dimensions. Each of top and bottom plates 20 and 21 are 20 constructed of two layers of rubber separated by a metal reinforcing sheet 27 and 28 respectively. The metal reinforcing sheets 27 and 28 provide added strength and rigidity to the top and bottom plates 20 and 21 as well as facilitating connection of the top and bottom plates 20 25 and 21 to the first and second uprights 22 and 23 by a plurality of bolts. The metal reinforcing sheets 27 and 28 are constructed of, for example, mild steel plate. The bottom plate 21 has a ridge 29 connected to the bottom surface at the inner end of the bottom plate 30 21. The ridge, in use, is adapted to sit on a frame at the discharge end of the grinding mill so as to support the discharge member 11 in use. The first and second uprights 22 and 23 in one embodiment are substantially rectangular prismatic in 35 shape and are cast from metal, for example, white iron steel. The first and second uprights 22 and 23 are arranged, in use, so that their longest side is orientated WO 2005/016538 PCT/AU2004/001094 -6 radially with respect to the clamping ring 12. The second upright 23 extends along the radial length of the body portion 19. The first upright 22 extends from the outer end of the body portion 19 only partially along the radial 5 length of the body portion 19. In an alternative embodiment, the first and second uprights 22 and 23 have a non-constant radial cross-section, whereby the first and second uprights 22 and 23 have portions which are thinner and thicker 10 depending on which regions of the first and second uprights 22 and 23, in use, are subjected to the most wear. By thinning out the regions of the uprights 22 and 23 which are not subjected to much wear, the weight of the discharge cone member 11 can be reduced. Furthermore, by 15 thickening the regions of the uprights 22 and 23 which experience the most wear, the operational life of the discharge cone members-11 can be extended. The exact shaping of the first and second uprights 22 and 23 is dependent on the grinding mill in which the discharge cone 20 member 11 is to be used. The second upright 23 has a steel rib 34 extending along the side of the second upright 23 corresponding to the direction in which the grinding mill, in use, rotates. The steel rib 34 is located towards the 25 top of the second upright 23 and has a substantially rectangular cross-section, so that the lower surface of the steel rib 34 forms a continuous surface with the bottom surface of the top plate 20. The purpose of the steel rib 34 will become apparent further on in the 30 specification. The nose cone 24 has a central vane 30 and a downwardly curving flange 31 extending from either side of the central vane. In use, the nose cone 24 is arranged so that the lower surface of -downwardly curving flange 31 35 forms a substantially continuous surface with the bottom surface of the top plate 20. The central vane 30 is i ntegrally formed with the second upright 23, such that WO 2005/016538 PCT/AU2004/001094 -7 the second upright 23 and the nose cone 24 are cast as a single piece. Each discharge cone member 11 also has a clamping tongue 25 integrally formed at the inner end of the nose 5 cone 24, i.e. remote from the body portion 19. The clamping tongue 25 is adapted, in use, to connect each discharge cone member 11 to the clamping ring 12. The clamping ring 12 is an annular disc with a raised outer edge 40, the outer edge 40 being shaped to have a close 10 fit with the top surface of the nose cone 24. This helps prevent the loss of fines from the discharge end of the grinding mill, by deflecting the fines into a trunion (not shown). The clamping ring 12 is provided with apertures, evenly spaced around the disc. The clamping tongue 25 15 also has an aperture whereby, attachment of the discharge cone member 11 is achieved by aligning the aperture in the clamping tongue 25 with one of the apertures in the clamping ring 12 and passing a bolt therethrough. The clamping ring 12 is cast from a metal, for example steel. 20 In use, the material enters the body portion 19 of the discharge cone member 11 through a passageway 32 created between the top and bottom plates 20 and 21 and the first and second uprights 22 and 23. Material will also enter through a similar passageway created between 25 the top and bottom plates 20 and 21 of two neighbouring discharge cone members lla and lb and the first upright 22 of one discharge cone member lla and the second upright 23 of a neighbouring discharge cone member 11b. The material then passes between the top and 30 bottom plates 20 and 21 under gravitational and centrifugal force. The majority of the material moves along the side of the second upright 23 corresponding to the direction in which the grinding mill, in use, rotates. Because this results in a higher localised region of wear, 35 the steel rib 34 is provided to reduce the wear to the rubber top plate 20. Material exiting the grinding mill exits the WO 2005/016538 PCT/AU2004/001094 -8 discharge cone member 11 through exit 33, which is formed by the central vanes 30, the bottom plates 21 and opposing sides of the flanges 31 of the two neighbouring discharge cone members lla and lib. A majority of the impact and 5 wear caused by the material exiting the discharge cone members lla and llb occurs along the bottom surface of the flange 31 and the side walls of the central vane 30. Each discharge cone member 11 also has a lifting boss 26, located on the axis perpendicular to the top and 10 bottom plates 20, 21, the axis passing through the centre of mass of the discharge member 11. The axis also passes through the second upright 23, such that the lifting boss is integrally formed with the second upright 23 and projects through the top plate 20. The lifting boss 26 is 15 therefore also cast from metal for example white iron steel. The lifting boss 26, is adapted, in use, to facilitate lifting and maneuvering of the discharge cone member 11 for installation into and/or removal from the grinding mill. Alternatively, each discharge cone member 20 11 may be provided with a pair of lifting lugs, positioned either side of the axis which passes through the centre of mass of the discharge member 11 such that the lifting lugs facilitate stable lifting-and maneuvering of the discharge member 11. 25 In the claims which follow and in the preceding description of the invention, 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 in an inclusive sense, 30 ie. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

1. A discharge cone for a grinding mill, the discharge cone comprising a plurality of discharge members, each discharge member being formed from a composite of 5 materials and comprising a body portion and a nose cone, the body portion comprising a top plate and a bottom plate separated by at least one upright member disposed between the top and bottom plates, the entirety of the nose cone being cast from metal, the nose cone projecting from the 10 body portion towards the centre of the discharge cone and integrally formed with a part of the body portion.

2. A discharge cone as claimed in claim 1, wherein the body portion is formed from a composite of rubber and metal. 15

3. A discharge cone as claimed in either claims 1 or claim 2, wherein the top and bottom plates are both formed from a composite of rubber and metal.

4. A discharge cone as claimed in any one of the preceding claims, wherein the top and bottom plates 20 each comprise a metal reinforcing sheet disposed between layers of rubber.

5. A discharge cone as claimed in any one of the preceding claims, wherein the nose cone comprises a central vane and a downwardly curving flange extending from 25 either side of the vane.

6. A discharge cone as claimed in claim 5, wherein the flange is arranged to form a substantially continuous surface with a bottom surface of the top plate.

7. A discharge cone as claimed in either claim 30 5 or claim 6, wherein the central vane is integrally formed with one of the at least one uprights.

8. A discharge cone as claimed in any one of the preceding claims, wherein one or more of the at least one uprights includes a metal rib extending along the side 35 of the uprights(s) corresponding to the direction in which the grinding mill, in use rotates, the metal rib arranged, in use to form a continuous surface with the bottom surface of the top plate. 2133934 1 (GHMatters) 21/12/09 WO 2005/016538 PCT/AU2004/001094 - 10

9. A discharge cone as claimed in any one of the preceding claims, wherein each of the discharge members further comprises a lifting boss, located on the axis perpendicular to the top and bottom plates, the axis 5 passing through the centre of mass of the discharge member, the lifting boss adapted for use in manoeuvring the discharge member for installation and/or removal from the grinding mill.

10. A discharge cone as claimed in claim 9, 10 wherein the lifting boss is integrally formed with one of the at least one uprights and projects through the top plate.

11. A discharge cone as claimed in any one of claims 1-8, wherein each of the discharge members further 15 comprises a pair of lifting lugs, located on the top surface of the top plate and positioned either side of the axis which passes through the centre of mass of the discharge member.

12. A discharge cone as claimed in any one of 20 the preceding claims, wherein the nose cone further comprises a clamping tongue at the end of the nose cone which projects towards the centre of the discharge cone, the clamping tongue adapted, in use, to allow the discharge member to be fixed in position in the grinding 25 mill.

13. A discharge member as claimed in claim 12, wherein the clamping tongue is adapted, in use, to connect each discharge member to a clamping ring.

14. A discharge cone as claimed in any one of 30 the preceding claims, wherein the at least one upright has a non-constant radial cross-section.

15. A discharge member for a grinding mill according to any one of claims 1-14.

16. A discharge member for a grinding mill 35 substantially as hereinbefore described with reference to the accompanying drawings. WO 2005/016538 PCT/AU2004/001094 - 11

17. A discharge cone for a grinding mill substantially as hereinbefore described with reference to the accompanying drawings. 5