DISCHARGE END WALL INSERTS

Abstract

A sleeve insert for covering one or more selected surfaces of one or more pulp lifters of a discharge end assembly including a discharge end wall of a mill shell partially defined by an outer perimeter wall thereof, the pulp lifters being mounted on the discharge end wall. The sleeve insert is formed to cover the selected surfaces to mitigate wear to which the selected surfaces are subjected when the sleeve insert is located in a predetermined position relative to the selected surfaces.

Claims

1. A discharge end wall system mountable on a discharge end wall of a mill shell in a grinding mill, the mill shell being rotatable about an axis of rotation thereof in a direction of rotation to produce a pulp comprising ore particles and water from a charge comprising ore and water via comminution, the discharge end wall being partially defined by an outer perimeter wall of the mill shell and comprising a central hole through which the pulp exits the mill shell, the discharge wall system comprising: a discharge end assembly comprising: a plurality of pulp lifters positionable on the discharge end wall for guiding the pulp toward the central hole, each said pulp lifter extending between an outer end located proximal to the outer perimeter wall and an inner end located proximal to the central hole; the pulp lifters being arranged in respective pairs thereof comprising adjacent ones of the pulp lifters, each said pair respectively comprising a leading one of the pulp lifters in the pair and a trailing one of the pulp lifters in the pair relative to the direction of rotation, said pairs partially defining pulp chambers therebetween respectively through which the pulp is at least partially directed to the central hole, each said pulp chamber comprising an intake portion thereof located proximal to the outer perimeter wall; each said leading one and each said trailing one of the pulp lifters in each said pair being at least partially defined by a ridge surface thereof spaced apart from the discharge end wall by a leading side of the pulp lifter and a trailing side of the pulp lifter relative to the direction of rotation; at least one discharge grate at least partially covering the intake portions of the pulp chambers, said at least one discharge grate comprising apertures therein to permit the pulp to flow therethrough into the intake portions thereof; and a plurality of sleeve inserts, each said sleeve insert being formed to be mounted on a selected one of the pulp lifters at an intermediate location thereon and inwardly relative to the intake portions of the pulp chambers partially defined by the selected one of the pulp lifters, each said sleeve insert comprising a wear-resistant material and being formed for at least partially covering at least one selected surface of at least one of the trailing and leading sides of the selected one of the pulp lifters that is subjected by the charge to wear in the absence of the sleeve insert, for mitigating the extent to which said at least one selected surface is subjected to wear as the mill shell rotates.

2. The discharge end wall system according to claim 1 in which each said sleeve insert comprises: a central element formed for engagement with the ridge surface of the selected one of the pulp lifters; and at least one side element connected with the central element, said at least one side element being formed to at least partially cover a portion of said at least one of the trailing side and the leading side respectively of the selected one of the pulp lifters on which said at least one selected surface is located.

3. The discharge end wall system according to claim 1 in which said at least one selected surface is on the trailing side of the selected one of the pulp lifters, and said at least one side element is formed to cover said at least one selected surface.

4. The discharge end wall system according to claim 2 in which: the selected one of the pulp lifters comprises at least one hole in the ridge surface thereof; the central element comprises an aperture alignable with said at least one hole when said at least one sleeve insert is mounted on the selected one; and the discharge end wall system additionally comprises a fastener receivable in the aperture and said at least one hole, to secure the sleeve insert to the selected one of the pulp lifters.

5. The discharge end wall system according to claim 2 in which each said sleeve insert comprises a pair of side elements, said side elements being formed to cover portions of the trailing side and the leading side respectively of the selected one of the pulp lifters, said side elements being formed with respective thicknesses thereof based on a wear pattern developed on the selected one of the pulp lifters in the absence of said sleeve insert, to mitigate the extent to which the selected one of the pulp lifters is subjected to wear.

6. A grinding mill comprising: a mill shell comprising a mill shell chamber therein and having an outer perimeter wall partially defining a discharge end wall of the mill shell, rotatable in a direction of rotation to produce a pulp including ore particles and water from a charge comprising ore and water, via comminution; the discharge end wall having a central hole therein through which the pulp exits the mill shell; a discharge end assembly comprising: a plurality of pulp lifters positioned on the discharge end wall for guiding the pulp toward the central hole, each said pulp lifter extending between an outer end located proximal to the outer perimeter wall and an inner end located proximal to the central hole; the pulp lifters being arranged in respective pairs thereof comprising adjacent ones of the pulp lifters, each said pair comprising a leading one of the pulp lifters in the pair and a trailing one of the pulp lifters in the pair relative to the direction of rotation, said pairs partially defining respective pulp chambers therebetween respectively through which the pulp is at least partially directed to the central hole, each said pulp chamber comprising an intake portion thereof located proximal to the outer perimeter wall; each said leading one and each said trailing one of the pulp lifters in each said pair being at least partially defined by a ridge surface thereof spaced apart from the discharge end wall by a leading side of the pulp lifter and a trailing side of the pulp lifter relative to the direction of rotation; at least one discharge grate at least partially covering the intake portions of the pulp chambers, said at least one discharge grate comprising apertures therein to permit the pulp to flow therethrough into the intake portions thereof; and a plurality of sleeve inserts, each said sleeve insert being formed to be mounted on a selected one of the pulp lifters at an intermediate location thereon inwardly relative to the intake portions of the pulp lifters partially defined thereby, each said sleeve insert being formed for at least partially covering at least one selected surface on at least one of the trailing and leading sides of the selected one of the pulp lifters therefor that is subjected by the charge to wear in the absence of the sleeve insert, for mitigating the extent to which said at least one selected surface is subjected to wear as the mill shell rotates.

7. The grinding mill according to claim 6 in which the sleeve insert comprises: a central element formed for engagement with the ridge surface of the selected one of the pulp lifters; and at least one side element connected with the central element, said at least one side element being formed to at least partially cover at least one of a portion of the trailing side and a portion of the leading side of the selected one of the pulp lifters.

8. The grinding mill according to claim 6 in which said at least one selected surface is on the trailing side of the selected one of the pulp lifters relative to the direction of rotation.

9. The grinding mill according to claim 7 in which: the selected one of the pulp lifters comprises at least one hole in the ridge surface thereof; the central element comprises an aperture alignable with said at least one hole when said at least one sleeve insert is mounted on said pulp lifter; and the central element is securable to the pulp lifter by a fastener receivable in the aperture and the hole.

10. The grinding mill according to claim 7 in which the sleeve insert comprises a pair of side elements, said side elements being formed to cover respective portions of the trailing side and the leading side of the selected one of the pulp lifters, said side elements being formed with respective thicknesses based on a wear pattern developed on the selected one of the pulp lifters in the absence of the sleeve insert, to mitigate the extent to which the selected one of the pulp lifters is subjected to wear.

11. A method of mitigating the extent to which at least one selected surface on a pulp lifter that is positioned on a discharge end wall of a mill shell partially defined by an outer perimeter wall of the mill shell and comprising a central hole through which pulp exits the mill shell, the mill shell being rotatable about its axis in a direction of rotation to produce the pulp comprising ore particles and water via comminution, said at least one selected surface being positioned at an intermediate location thereon between an outer end proximal to the outer perimeter wall and an inner end of the pulp lifter proximal to the central hole and inwardly relative to intake portions of pulp chambers respectively defined by the pulp lifter and located proximal to the outer perimeter wall, the pulp lifter comprising a ridge surface spaced apart from the discharge end wall by a trailing side and a leading side relative to the direction of rotation, the method comprising: (a) locating said at least one selected surface at the intermediate location on the pulp lifter on at least one of the trailing side and the leading side of the pulp lifter; (b) providing a sleeve insert formed to be positioned at the intermediate location on the pulp lifter inwardly relative to the intake portions to cover said at least one selected surface; (c) positioning the sleeve insert on the pulp lifter, to cover said at least one selected surface; and (d) securing the sleeve insert to the pulp lifter at the ridge surface thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention will be better understood with reference to the attached drawings, in which:

[0036] FIG. 1A (also described previously) is a schematic illustration showing certain selected solid particles in selected pulp chambers located at first locations between the nine o'clock and three o'clock positions thereof and moving along a clockwise rotation path;

[0037] FIG. 1B (also described previously) is a schematic illustration of the pulp chambers of FIG. 1A and the selected solid particles therein further along the rotation path;

[0038] FIG. 1C (also described previously) is a schematic illustration of the pulp chambers of FIGS. 1A and 1B and the selected solid particles therein further along the rotation path;

[0039] FIG. 1D (also described previously) is a longitudinal cross-section of a conventional grinding mill, drawn at a smaller scale;

[0040] FIG. 2A is an elevation view of an embodiment of a discharge end wall system of the invention including an embodiment of a pulp chamber insert of the invention, drawn at a larger scale;

[0041] FIG. 2B is a cross-section taken along line B-B in FIG. 2A, drawn at a larger scale;

[0042] FIG. 2C is a part of the discharge end wall assembly of FIG. 2A, drawn at a larger scale;

[0043] FIG. 3 is an isometric view of the discharge end wall assembly of FIG. 2A, drawn at a smaller scale;

[0044] FIG. 4A is a top view of an embodiment of an insert of the invention, drawn at a larger scale;

[0045] FIG. 4B is an elevation view of a portion of an embodiment of a discharge end wall assembly of the invention including the insert of FIG. 4A, drawn at a smaller scale;

[0046] FIG. 4C is a cross-section taken along line A-A in FIG. 4B;

[0047] FIG. 4D is a top view of an alternative embodiment of the insert of the invention, drawn at a larger scale;

[0048] FIG. 4E is a top view of another alternative embodiment of the insert of the invention;

[0049] FIG. 5 is an exploded isometric view of the insert of FIG. 4C and a portion of a pulp chamber in which the insert is positionable;

[0050] FIG. 6A is an elevation view of an alternative embodiment of a discharge end wall assembly of the invention, drawn at a smaller scale;

[0051] FIG. 6B is a cross-section taken along line D-D in FIG. 6A, drawn at a larger scale;

[0052] FIG. 6C is an elevation view of a pulp lifter of the discharge end wall assembly of FIG. 6A, drawn at a larger scale;

[0053] FIG. 6D is an elevation view of a portion of the discharge end wall assembly of FIG. 6A, drawn at a larger scale;

[0054] FIG. 7 is a longitudinal cross-section of an embodiment of a grinding mill of the invention, drawn at a smaller scale; and

[0055] FIG. 8 is a cross-section of the discharge end wall assembly of FIG. 2A taken along line C-C in FIG. 2A.

DETAILED DESCRIPTION

[0056] In the attached drawings, like reference numerals designate corresponding elements throughout. In particular, to simplify the description, the reference numerals previously used in FIGS. 1A-1D are used again in connection with the description of the invention hereinafter, except that each such reference numeral is raised by 100 (or by whole number multiples thereof, as the case may be), where the elements described correspond to elements referred to above.

[0057] Reference is first made to FIGS. 2A-7 to describe an embodiment of a discharge end wall system 240 mounted on a discharge end wall 227 of a mill shell 223 in a grinding mill 221, the mill shell 223 being rotatable about an axis of rotation thereof AX.sub.I in a direction of rotation to produce the pulp including ore particles and water. The discharge end wall 227 is partially defined by an outer perimeter wall 226 of the mill shell 223 and includes a central hole 224 through which the pulp exits the mill shell 223. In one embodiment, the discharge wall system 240 preferably includes a discharge end assembly 242 that includes the discharge end wall 227 and the outer perimeter wall 226 and a number of pulp lifters 222 radially arranged on the discharge end wall 226 relative to the axis of rotation AX.sub.1. It is preferred that pairs of adjacent ones of the pulp lifters each respectively include a leading one of the pulp lifters in the pair and a trailing one of the pulp lifters in the pair relative to the direction of rotation, as will be described. The pairs of pulp lifters partially define respective pulp chambers 228 therebetween through which the pulp is at least partially directed to the central hole 224. Preferably, the discharge end wall system 240 also includes one or more inserts 244 for covering one or more selected surfaces 246 (FIG. 4C) of the discharge end assembly 242, to mitigate the extent to which the selected surface 246 is subjected to wear due to movement of the pulp in the pulp chambers 228, as will also be described.

[0058] As can be seen, for example, in FIGS. 4A-4C, it is also preferred that the discharge end wall system 240 includes means 248 for securing the insert 244 in a predetermined position relative to the selected surface 246, to cover the selected surface 246.

[0059] In one embodiment, the discharge end wall system 240 preferably also includes one or more discharge grates 250 (FIG. 4C) positioned on the pulp chambers 228. The discharge grates 250 include apertures 252 therein to permit the ore particles and the water to flow therethrough into the pulp chambers 228. It is preferred that the insert 244 is securable in the predetermined position relative to the selected surface 246 between the discharge grate 250 and the discharge end assembly 242, to cover the selected surface 246 (FIG. 4C). In one embodiment, therefore, the means 248 preferably includes the discharge grate 250 and the fasteners 254. In FIG. 4B, for instance, the insert 244 is shown installed in the pulp chamber 228, and one of the fasteners 254 is shown in place. It will be understood that the discharge grate 250 is omitted from FIG. 4C for clarity of illustration.

[0060] In one embodiment, the insert 244 preferably is formed to be positioned in at least part of a selected one of the pulp chambers 228 to cover the selected surface 246 (FIGS. 4B, 4C). As can be seen in FIG. 4B, the pulp chamber 228 preferably is at least partially defined by a pair of pulp lifters. The direction of rotation is indicated by arrow B.sub.1. For clarity of illustration, the leading one of the pair of pulp lifters partially defining the pulp chamber 228 illustrated in FIG. 4B is identified in FIG. 4B by reference numeral 222.sub.L, and the trailing one of the pair is identified by reference numeral 222.sub.T.

[0061] As noted above, it has been found that the extent to which the pulp chambers in the discharge end wall in a particular grinding mill are subjected to wear varies. This is believed to be due to a number of factors, including, for example, the arrangements of pulp lifters of different lengths. Because the wear to which the pulp chambers are subjected generally varies significantly, the optimum designs of the inserts and their optimum distribution or positioning in the discharge end assembly 242 may vary widely. Preferably, the design of each insert 244 is based on the pattern of wear in the pulp chamber in which the insert is to be installed, as will be described.

[0062] In addition, because the patterns of wear in each part of the discharge end assembly 242 vary, it is preferred that the inserts 244 are individually formed, or tailored, to cover specifically identified selected surfaces 246. For instance, the wear in two adjacent pulp chambers may be sufficient to require pulp chamber inserts in each, however, if the wear patterns in each of the two pulp chambers are different (as is often the case), then the inserts formed to cover the selected surfaces in each of the two pulp chambers also are formed or tailored to have different configurations or shapes, and they are also formed to be secured into different predetermined positions respectively.

[0063] As can be seen in FIGS. 4B and 4C, the pulp chamber insert 244 preferably is secured in place by the discharge grate 250 that is secured to the discharge end assembly 242 by fasteners 254. That is, the pulp chamber insert 244 preferably is held in the predetermined position therefor (i.e., so that the insert 244 covers the selected surface 246) by the fasteners that hold discharge grate(s) in position on the discharge end assembly 242. In one embodiment, the pulp chamber insert 244 preferably includes flanges 256, 258 that engage ridge surfaces 260, 262 of the pulp lifters 228 (FIG. 4B). Preferably, the flanges 256, 258 are secured to, or integrally formed with, sidewalls 264 of the insert 244.

[0064] It will be understood that, in order to install the pulp chamber insert 244 once it is formed, it is positioned in a preselected part of the pulp chamber 228 (FIG. 4B). Preferably, the pulp chamber insert 244 is formed and sized to fit in the preselected part. The insert 244 is formed and positioned to cover the selected surface 246, and it will be understood that, in FIGS. 4B and 4C, the selected surface 246 is at least a portion of the part of the pulp chamber 228 that is covered by the pulp chamber insert 244. Preferably, the pulp chamber's floor is a part of the discharge end wall 227. The outer perimeter wall 226 also partially defines the pulp chamber 228, as do the trailing side TS of the leading pulp lifter 222.sub.L and the leading side LS of the trailing pulp lifter 222.sub.L (FIG. 4B).

[0065] In one embodiment, the pulp chamber insert 244 preferably includes one or more end walls 266 and a floor portion 268 connected to the sidewalls 264 (FIG. 4A). As will be described, because the form of the pulp chamber insert is determined according to the position and shape of the selected surfaces that are to be covered, other embodiments of the pulp chamber insert may have other forms.

[0066] When the floor portion 268 of the pulp chamber insert 244 is positioned on the discharge end wall 227, the end wall 266 preferably engages the outer perimeter wall 226. Also, in such position, the sidewalls 264 of the pulp chamber insert 244 preferably engage the leading and trailing sides LS, TS of the trailing and leading pulp lifters 222.sub.T, 222.sub.L respectively. In addition, and as can be seen in FIG. 4B, when the pulp chamber insert 244 is so positioned in the part of the pulp chamber 228, it is preferred that the flanges 256, 258 engage the ridge surfaces 260, 262 of the trailing and leading pulp lifters 222.sub.T, 222.sub.L respectively.

[0067] From the foregoing, it can be seen that the pulp chamber insert 244 is formed to fit into the pulp chamber 228 so that its parts engage corresponding elements at least partially defining the pulp chamber 228, to locate the pulp chamber insert 244 so that it covers the selected surface(s) 246 when the insert 244 is in its predetermined position relative to the selected surface(s) 246. The pulp chamber insert 244 preferably is tailored to address the patterns of wear, whether resulting from carryover or otherwise.

[0068] As can also be seen in FIG. 4B, in one embodiment, the flanges 256, 258 preferably include openings 270 formed for alignment with holes 272 in the ridge surfaces 260, 262. It will be understood that the holes 270 and the holes 272 are shown aligned in FIG. 4B. It will also be understood that the holes 272 preferably are also aligned with additional holes (not shown) in the grates 250 through which fasteners 254 are insertable, to secure the grates 250 to the ridge surfaces of the pulp lifters 222.sub.T, 222.sub.L respectively. Based on the foregoing, it can be seen that the flanges 256, 258 are positioned between the ridge surfaces of the pulp lifters and the grates and are held in place between the grates and the ridge surfaces by the fasteners.

[0069] Preferably, the pulp chamber insert 244 is made of any suitable material or materials, preferably selected at least in part for their ability to resist the wear to which the pulp chamber insert is subjected by the solid particles in the pulp, i.e., both carryover and non-carryover. It will be understood that the pulp chamber insert 244 may be made of highly wear-resistant material or materials. For example, the wear-resistant material or materials may be any suitable metallic or non-metallic material or materials. The insert also may be any suitable thickness or thicknesses. In each grinding mill, the parameters may differ widely, and the optimum thicknesses of material for any particular pulp chamber insert is determined according to a number of factors specific to the mill. As will be described, in one embodiment, the thicknesses of different portions of the pulp chamber insert may also vary, in order to take into account patterns of wear in the respective pulp chambers.

[0070] From the foregoing, it can be seen that, when the pulp chamber insert 244 is in the predetermined position therefor, the pulp chamber insert 244 protects selected surfaces 246 of the pulp lifters and the elements that, at least partially, define the pulp chamber in which the insert is positioned.

[0071] One of the advantages of the pulp chamber insert is that it may be installed when the discharge grates are replaced. Those skilled in the art would be aware that the discharge grates generally are replaced more frequently than, e.g., the pulp lifters. From the foregoing, it can be seen that the pulp chamber inserts 244 may be installed economically at a time when the grinding mill 221 is down for replacement of the discharge grates. Because of this, the inserts 244 may be installed without such installation imposing significant additional downtime (i.e., additional expense) beyond the downtime required for replacement of discharge grates.

[0072] The pulp chamber insert 244 of the invention also has the advantage that the insert 244 preferably is held in place by the fasteners that secure the grates to the pulp lifters. Accordingly, the insert 244 preferably may be retrofitted relatively easily, being held in the predetermined position therefor using the fasteners previously used only to secure the discharge grates to the discharge end assembly 242.

[0073] As can be seen in FIG. 7, in one embodiment, the grinding mill 221 preferably includes the pulp chamber inserts 244 installed in selected ones of the pulp chambers 228, as described above. From the foregoing, it will be understood that the pulp chamber inserts installed in the grinding mill 221 are not necessarily the same, but instead each preferably is formed for use in a specific pulp chamber, to address the individual patterns of wear in each pulp chamber. Also, and as described above, the patterns of wear may be such that certain pulp chambers do not have pulp chamber inserts installed therein, as there may be insufficient wear in such pulp chambers to warrant pulp chamber inserts therein. As illustrated in FIG. 7, as an example, the pulp chamber inserts 244 are installed in pulp chambers identified for convenience as 228.sub.U and 228.sub.L.

[0074] As can be seen in FIG. 7, in use, a charge CH.sub.2 preferably is introduced into a mill shell chamber 225 of the mill shell 223, as indicated by arrow IN.sub.2. The top surface of the charge CH.sub.2 is indicated at A2. As is known, the grinding mill 221 preferably includes the mill shell 223 rotatable about the axis AX.sub.1 (FIG. 7). As the mill shell 223 rotates, the ore in the charge is ground into finer ore particles that are included in the pulp that is ultimately located in the pulp chambers 228, as indicated by arrows OP.sub.2 in FIG. 7. (Those skilled in the art would appreciate that the ore and the ore particles may include waste and waste particles.) Subject to carryover, the pulp exits the grinding mill 221 via the central hole 224 in the discharge end wall 227, as indicated by arrow EX.sub.2 in FIG. 7.

[0075] Preferably, the pattern of wear in a particular pulp chamber is taken into account in the design of the pulp chamber insert that is to be installed in that pulp chamber. For example, a sidewall's thickness may be increased in a portion thereof if excessive wear were found on the corresponding portion of the wall of the pulp chamber. It will be understood that other parameters (e.g., expected tph throughput, speed of rotation) preferably are also taken into account in the pulp chamber insert design, particularly if any such parameters are expected to be changed.

[0076] In an alternative embodiment, an insert 344 of the invention preferably additionally includes one or more cushion elements 376 formed to be positioned adjacent to one or more preselected portions 378 of a selected surface 346 (FIG. 2B) when the insert 344 is positioned in the predetermined position therefor, to attenuate the extent to which the selected portion 378 is subjected to wear. The insert 344 is shown in FIG. 4D. A discharge end wall system 340 including the insert 344 is illustrated in FIG. 2A.

[0077] For instance, the insert 344 may include portions thereof that are selectively thickened or otherwise formed to provide protection from wear to specific parts of the elements that partially define the pulp chamber 328 (FIG. 5). The thickened portions preferably are shaped and positioned to correspond to patterns of wear inside the pulp chambers respectively, and are referred to herein as the cushion elements. As can be seen, for instance, in FIG. 4D, in one embodiment, the insert 344 preferably includes an end wall cushioning element 380 formed to provide extra protection to the outer wall 326 of the pulp chamber 328 (FIG. 5). This embodiment of the insert 344 also includes a sidewall cushioning element 382 that increases the thickness of a selected sidewall 364 of the insert 344 (FIG. 5).

[0078] It will be understood that the form, and positioning, of the cushion elements 376 depends on the form and positioning of the selected surface 346, and also of the preselected portion 378 of the selected surface 346. It will also be understood that, although the preselected portion 378 is within the selected surface 346, the preselected portion 376 may occupy the entire selected surface 346. The preselected portion is an area on the surface(s) of the discharge end assembly 342 which is subjected to wear to a much greater extent than the surface areas of the discharge wall assembly that are adjacent to it. It is intended that the cushion elements 376 are formed and located (in the insert 344) to provide additional protection from wear to the preselected portion(s) 378.

[0079] For example, the insert 344 illustrated in FIG. 4D has at least two cushion elements, identified by reference numerals 380 and 382 respectively. It can be seen that the cushion elements 380, 382 are positioned in order to protect the right-hand side of the outer perimeter wall 326 (as presented in FIG. 4D), and generally the entire leading side LS of the trailing pulp lifter 322.sub.L (FIG. 5). As can be seen in FIG. 2B, the pulp lifter insert 344 has a profile selected to attenuate the wear to which the selected portion has been subjected. Preferably, the cushion elements are included in the insert 344 which is formed when the preselected portion of the selected surface 346 is an area of excessive wear in a discharge end assembly 342 (FIG. 2A). For the purposes hereon, excessive wear means that the preselected portion 378 is worn to a greater extent than the balance of the selected surface, or selected surfaces located elsewhere in the discharge end assembly 342.

[0080] For example, in FIG. 2B, the insert 344 is shown secured in the predetermined position therefor, in a pulp chamber 328. The cushion element 376 is shown as being located adjacent to the preselected portion 378 on the leading pulp lifter 322.sub.L for the pulp chamber 328. It can also be seen that the selected surface 346 includes not only the preselected portion 378, but also parts of a discharge end wall 327 and the trailing pulp lifter, identified as 322.sub.L in FIGS. 2B and 2C for clarity of illustration. However, as can also be seen in FIG. 2B, the preselected portion 378 also includes a part of the discharge end wall 327.

[0081] It is preferred that the insert 344 includes flanges 356, 358 that are located between a discharge grate 350 and respective ridge surfaces 360, 362 of the pulp lifters 322, 322 when the insert 344 is in the predetermined position therefor (FIGS. 2B, 2C). Preferably, and as shown in FIG. 2B, the discharge grate 350 is secured to the discharge end assembly 342 by fasteners 354. (The discharge grate 350 is omitted from FIG. 2C for clarity of illustration.) Those skilled in the art would appreciate that the fasteners 354 preferably are those used to secure the discharge grate 350 to the pulp lifters in the absence of the insert 344, i.e., the insert 344 is conveniently retrofitted using pre-existing elements of the discharge grate and the discharge end assembly 342.

[0082] In FIG. 2A, a number of the inserts 344 are shown mounted in the discharge end assembly 342. The direction of rotation is indicated by arrow B.sub.i. It will be understood that discharge grates are omitted from FIG. 2A for clarity of illustration. As can be seen in FIG. 2A, which is exemplary only, there are several pulp chambers 328 in which the insert 344 is not installed. The flanges 356, 358 can also be seen in FIGS. 4D and 5. In the example illustrated in FIG. 2A, the wear to which the discharge end assembly 342 is subjected has resulted in the pattern of installed inserts 344 that is shown therein. Also, for clarity of illustration, the inserts 344 that are shown in FIG. 2A are substantially the same. As noted above, however, each of the inserts 344 preferably is tailored for the wear patterns in each individual pulp chamber.

[0083] An example of an insert 344 that is formed to include one or more cushion elements 378 in a different configuration is shown in FIG. 4E. As can be seen in FIG. 4E, in this embodiment, the cushion elements 378 are located on the left-hand side of the insert 344, as illustrated. Those skilled in the art would appreciate that the locations, shape and dimensions of the cushion elements on the insert may vary as required, depending on the pattern of wear on the discharge end assembly.

[0084] As can be seen in FIG. 5, to install the insert 344 (shown in FIGS. 4D and 5) in the pulp chamber 328, the insert 344 is moved into the pulp chamber 328 (as indicated by arrow F). In one embodiment, the pulp chamber insert 344 preferably includes sidewalls 364 and an end wall 366 connected to a floor portion 368 thereof.

[0085] For convenience, in FIG. 5, the leading pulp lifter relative to the pulp chamber 328 associated therewith is identified by reference numeral 322.sub.L, and the trailing pulp lifter is identified by reference numeral 322.sub.T. When the pulp chamber insert 344 is in the predetermined position relative to the selected surface 346, the floor portion 368 engages the discharge end wall 327, the sidewalls 364 engage the trailing side TS.sub.3 of the leading pulp lifter 322.sub.L and the leading side LS.sub.3 of the trailing pulp lifter 322.sub.T respectively, and the end wall 366 engages the outer perimeter wall 326. Also, the flanges 356, 358 engage the ridge surfaces 360, 362 of the trailing and leading pulp lifters 322.sub.T, 322.sub.L respectively. It will be understood that openings 370 in the flanges 356, 358 align with the holes 372 in the ridge surfaces 360, 362 to permit insertion of the fasteners 364 (not shown in FIG. 5) therethrough, to secure the discharge grate 350 to the discharge end assembly 342 and also to secure the insert 344 in the predetermined position therefor.

[0086] Another alternative embodiment of an insert 444 of the invention is illustrated in FIGS. 3, 6A, and 6D. As can be seen in FIG. 6D, the insert 444 preferably includes a cushion element 478 that covers a portion of a discharge end wall 427 that is adjacent to a trailing side TS.sub.4 of a leading pulp lifter 422.sub.L. (The direction of rotation is shown by arrow B.sub.4 in FIG. 6D.) The insert 444 is mounted in a pulp chamber 428.

[0087] Another embodiment of the insert, referred to by reference numeral 444 for clarity of illustration, is also illustrated in FIG. 6D. As can be seen in FIG. 6D, the insert 444 preferably includes a cushion element 478 that covers a portion of the discharge end wall that is adjacent to a leading side LS.sub.4 of a trailing pulp lifter 422.sub.T. For clarity of illustration, the pulp chamber in which the insert 444 is installed is identified by reference numeral 428.

[0088] A discharge end wall system 440 including the inserts 444 and 444 is illustrated in FIGS. 3 and 6A.

[0089] As can be seen in FIGS. 1A-1C, the intermediate regions of the pulp lifters may be subjected to wear, to a significant extent. Also, and as illustrated in FIG. 1A, an inner end of the pulp lifter may be subjected to wear. The pulp lifters are particularly subjected to wear on their trailing sides, although there would also be wear on the leading side of each pulp lifter, due in part to the ore particles and water that enter the pulp chamber when it is immersed in the charge, in each rotation. Accordingly, in certain situations, the pulp lifters or certain parts thereof appear to be subjected to wear, while other elements of the discharge end assembly are subjected to much less wear. In these circumstances, the insert may be formed to fit onto the pulp lifter, in a sleeve-like arrangement.

[0090] Accordingly, a selected surface 546 may be located only on a selected one of the pulp lifters 522. An embodiment of an insert 544 of the invention is formed to fit onto a selected one of the pulp lifters 522 to cover the selected surface 546 of the selected one of the pulp lifters 522, to mitigate the extent to which the selected surface 546 is subjected to wear (FIG. 6B).

[0091] An embodiment of an insert 544 of the invention is illustrated in FIGS. 6A, 6B, and 6C, positioned on the pulp lifter 522 at an intermediate location 580. FIG. 6B is a cross-section taken along line F-F in FIG. 6A. As can be seen in FIG. 6B, in one embodiment, the insert 544 preferably includes an aperture 582 (FIG. 6C) alignable with a hole 572 in a ridge surface 560 of the pulp lifter 522, to enable the insert 544 to be secured to the pulp lifter 522 by a fastener (not shown in FIG. 6B) at the intermediate location.

[0092] In one embodiment, the insert 544 preferably includes side elements 583, 584 (FIG. 6B) that are joined to a central element 586 (FIG. 6C). Preferably, the aperture 582 is formed in the central element 586.

[0093] Those skilled in the art would appreciate that the insert 544 preferably is also held in place by a discharge grate (not shown in FIGS. 6A, 6B, 6C) which preferably is positioned on and engaged with the central element 586. The fasteners (not shown) otherwise used to hold the discharge grate on the pulp lifter preferably are positioned in the aperture and the hole to secure the grate to the pulp lifter 522, with the central element 586 of the insert 544 located therebetween.

[0094] In FIG. 6C, three inserts (identified for convenience as 544.sub.1, 544.sub.2, and 544.sub.3) are shown positioned on the pulp lifter 522. In the example illustrated in FIG. 6C, parts of the pulp lifter 522 that are positioned inwardly and outwardly relative to the inserts 544.sub.1, 544.sub.2, and 544.sub.3 are not covered by inserts.

[0095] It will also be understood that the insert 544 may have any suitable length. The thickness or thicknesses of the insert 544, and its length and shape, are determined according to the circumstances in the particular grinding mill in which the cap is installed.

[0096] For instance, in one embodiment, the pattern of wear on a particular intermediate portion of a particular pulp lifter preferably is taken into account in determining the length of the insert 544 that is to be positioned on such intermediate portion, and also the thickness (or thicknesses, as the case may be) of the insert 544. Other parameters may also be taken into account. It will be understood that, depending on the pattern of wear, forming the insert 544 to have different thicknesses thereof in view of the wear pattern may be optimal. It will also be understood, however, that it may be found to be optimal not to have the insert 544 positioned on every intermediate portion of every pulp lifter in a particular grinding mill.

[0097] Preferably, the insert 544 is made of any suitable highly wear-resistant material or materials. In much the same way as described above in relation to the pulp chamber insert, the material or materials are selected according to a number of factors, related, e.g., to the grinding mill and the charge, among other things. For instance, the insert 544 may be made of metallic or non-metallic material or materials.

[0098] The insert 544 protects intermediate portions of the pulp lifters, ultimately resulting in the pulp lifters have longer operational lives than would otherwise have been achieved. From the foregoing, it can also be seen that the insert 544 can be replaced relatively easily when the discharge grates are replaced.

[0099] From the foregoing, it can be seen that the invention preferably includes an embodiment of the grinding mill of the invention that includes one or more of the pulp chamber inserts 244 (FIG. 7).

[0100] In one embodiment, the grinding mill 221 preferably includes the mill shell 223 having the mill shell chamber 225 therein (FIG. 7) and having an outer perimeter wall 226 partially defining the discharge end wall 227 of the mill shell 229, rotatable in a direction of rotation to produce the pulp including ore particles and water. The discharge end wall 227 has a central hole 224 therein through which the pulp exits the mill shell 223. The discharge wall assembly 242 preferably includes the discharge end wall 227 and the outer perimeter wall 226 and a number of the pulp lifters 228 mounted on the discharge end wall 227. As described above, the pairs of adjacent ones of the pulp lifters respectively including the leading one of the pulp lifters in the pair and the trailing one of the pulp lifters in the pair relative to the direction of rotation. The pairs partially define respective pulp chambers therebetween through which the pulp is at least partially directed to the central hole. Also, the grinding mill includes the inserts 244, for covering the selected surface 246 of the discharge wall assembly 242, to mitigate wear to which the selected surface is subjected by movement of the pulp in the pulp chambers.

[0101] As can be seen in FIGS. 2A and 8, in one embodiment, the discharge wall assembly 342 preferably additionally includes a cone portion 386 for directing the pulp toward the central hole 324. The cone portion includes a number of vanes 388 radially aligned with selected ones of the pulp lifters 322, each vane 388 being mounted to the discharge end wall 327 and including an outer edge 390 thereof distal to the discharge end wall that at least partially defines an arc curved such that each of the vanes 388 directs the pulp toward the central hole 324.

INDUSTRIAL APPLICABILITY

[0102] Preferably, the insert is formed and installed in the discharge end assembly according to the following steps. First, the selected surface, being one of the surfaces in the discharge end assembly that is subjected to wear, is selected. It will be understood that the surfaces are selected based on the extent to which they are subjected to wear during the operation of the grinding mill. One way to assess which surfaces are subjected to more wear than others is a visual inspection of the discharge end assembly after operation for a period of time. Such visual inspection may be conducted, for instance, when discharge grates are removed in connection with routine maintenance. Next, the insert preferably is formed to cover the selected surface when positioned in the predetermined position relative to the selected surface, to mitigate the wear to which the selected surface is subjected. The discharge grate positioned between the mill shell chamber and the discharge end assembly is removed, to expose the selected surface. Preferably, the insert is positioned in the predetermined position therefor to cover the selected surface. The insert is secured in the predetermined position on the discharge end assembly.

[0103] Those skilled in the art would appreciate that the order in which the steps of one embodiment of the method of the invention are described above is not determinative, and certain of the steps may be performed in a sequence other than as set out above. For example, the discharge grate may first be removed, and following that, the selected surfaces may be selected.

[0104] In another embodiment of the method of the invention, first, a number of surfaces are selected. Next, a number of inserts preferably are formed to cover identified ones of the selected surfaces respectively, each insert being tailored to cover the identified ones of the selected surfaces respectively. As described above, the selected surfaces may have different shapes and sizes, and may be located in different locations of the discharge end assembly. Accordingly, it is preferred that the inserts for a particular discharge end assembly are respectively formed for specific (identified ones of the) selected surfaces. It is preferred that each insert is positioned in the predetermined position therefor respectively to cover the identified ones of the selected surfaces. Each of the tailored inserts preferably is secured in the predetermined position therefor respectively.

[0105] It is also preferred that each insert is secured in the predetermined position therefor by locating a portion of the insert between the discharge grate and the discharge end assembly, and attaching the discharge grate to the discharge end assembly, as described above.

[0106] In an alternative embodiment, the insert preferably includes one or more cushion elements formed to be located adjacent to one or more preselected portions of the selected surface when the insert is in the predetermined position therefor, to attenuate the extent to which the preselected portion is subjected to wear. As described above, the preselected portion may be, for example, a part of the surface of the discharge end assembly that is subjected to wear to a greater extent than the other parts of the selected surface(s).

[0107] In summary, the invention provides one or more inserts for covering the selected surface(s) of the discharge end assembly including the discharge end wall of a mill shell partially defined by the outer perimeter wall thereof and a number of pulp lifters mounted on the discharge end wall. The insert preferably is formed to cover the selected surface to mitigate wear to which the selected surface is subjected when the insert is located in the predetermined position relative to the selected surface.

[0108] In one embodiment, the insert is formed to fit into the pulp chamber. The pulp chamber insert preferably includes a floor, for covering a part of the discharge end wall, one or more sidewalls connected to the floor, for covering predetermined parts of the leading and trailing sides of the respective trailing and leading pulp lifters, and an end wall, for covering a part of the outer perimeter wall. The insert is formed to mitigate the extent to which the preselected part of the discharge end wall, the predetermined parts of the leading and trailing sides of the trailing and leading pulp lifters respectively, and the part of the outer perimeter wall are subjected to wear due to movement of the pulp in the pulp chamber, when the insert is positioned in the predetermined position.

[0109] In another embodiment, the insert is a sleeve insert formed to be positioned in the predetermined position therefor on the pulp lifter to cover the selected surface of the pulp lifter, for mitigating wear to which the selected surface is subjected.

[0110] It will be appreciated by those skilled in the art that the invention can take many forms, and that such forms are within the scope of the invention as claimed. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.