AU2021462235A1 - A mill and liner - Google Patents

Abstract

A mill including: a mill body having: a shell body; a feed end portion connected to the shell body to at least partly enclose one end of the shell body; a discharge end portion connected to the shell to at least partly enclose another end of the shell body; a shell liner connected to the shell body; a feed liner connected to the feed end portion; and a discharge liner connected to the discharge end portion, wherein the feed liner and the discharge liner extend transversely to the shell liner.

Description

A MILL AND LINER

TECHNICAL FIELD

[001] The present disclosure relates to a mill for carrying out grinding and liners for the mill. The invention also relates, but is not limited, to a method associated with the mill.

BACKGROUND

[002] Mills are commonly used in mining to grind and crush materials into smaller sizes. There are various types of mills but typically they include a shell in the form of a drum. The drum rotates and lifts material inside until the material reaches a point where gravity causes the material to fall and break down into a smaller size. The material also 'grinds' against each other in the drum, further refining the material. In the case of ball mills, steel balls are added to the drum to assist with grinding the ore. The tumbling balls capture the ore particles in ball/ball or ball/liner interactions and load them to the point of fracture.

[003] The choice of mill linings in mineral processes is critical to grinding efficiency, overall cost and product quality. Mill lining is a major cost in milling operations - accounting for up to 5% of the overall cost of mineral processing. The capital cost of the lining, together with the downtime and labour expense required to replace the liner, all contribute to mill costs. On the other hand, improved mill linings can often increase the efficiency of a mill by lowering energy consumption, increasing throughput and reducing maintenance costs down the line. As a result of an industry-wide demand for efficiency within a competitive economic climate, there are a number of liners that have been developed in an effort to increase wear resistance, improve grinding efficiency and reduce energy consumption.

[004] However, there are still various, interrelated issues with the design of mill linings that are not adequately addressed by current technologies. For example, appreciating the difference between feed, discharge and shell liners, and the connections therebetween, have a significant impact on service life and have been given inadequate attention. These non-obvious problems contribute to a number of issues and draw-backs in current mineral processing techniques.

[005] Any reference to or discussion of any document, act or item of knowledge in this specification is included solely for the purpose of providing a context for the present invention. It is not suggested or represented that any of these matters or any combination thereof formed at the priority date part of the common general knowledge, or was known to be relevant to an attempt to solve any problem with which this specification is concerned.

SUMMARY OF THE INVENTION

[006] In a first aspect, the present disclosure provides a mill including: a mill body having: a shell body; a feed end portion connected to the shell body to at least partly enclose one end of the shell body; a discharge end portion connected to the shell to at least partly enclose another end of the shell body; a shell liner connected to the shell body; a feed liner connected to the feed end portion; and a discharge liner connected to the discharge end portion, wherein the feed liner and the discharge liner extend transversely to the shell liner.

[007] In an embodiment, at least one of the feed liner or the discharge liner include steel and rubber. In an embodiment, the steel and rubber form a composite.

[008] In an embodiment, the rubber is natural rubber. In an embodiment, the steel is plain steel.

[009] In an embodiment, the rubber is moulded, at least partially, around portions of the steel. In an embodiment, the rubber is moulded, at least partially, around the steel.

[010] In an embodiment, the feed liner and the discharge liner are substantially the same. [011] In an embodiment, at least one of the feed liner or the discharge liner includes one or more steel plates extending around part of their outer perimeter. In an embodiment, the one or more steel plates are connected to the steel and rubber composite.

[012] In an embodiment, the one or more steel plates extend around part of the perimeter that is adjacent to a filler portion.

[013] In an embodiment, the one or more steel plates assist in minimising deformation in the rubber. In an embodiment, the one or more steel plates assist in minimising wear. For example, the one or more plates minimises wear by reducing deformation of the rubber which assists in avoiding shell wear when balls penetrate through a gap between a filler portion and least one of the feed liner or the discharge liner.

[014] In an embodiment, at least one of the shell liner, feed liner or the discharge liner include one or more lifter bars.

[015] In an embodiment, the one or more lifter bars include lifter bars of different height.

[016] In an embodiment, the one or more lifter bars include a plurality of lifter bars associated with the feed liner or the discharge liner, the plurality of lifter bars extending transversely to one another.

[017] In an embodiment, the plurality of lifter bars extend radially towards a trunnion.

[018] In an embodiment, lifter bars associated with the shell liner extend parallel to one another.

[019] In an embodiment, the mill includes a filler portion between the shell liner and at least one of the feed liner or the discharge liner.

[020] In an embodiment, the filler portion includes a chromoly steel. In an embodiment, the hardness of the chromoly steel of the filler portion is between 325HB to 550HB.

[021] In an embodiment, the filler portion is substantially in the form of a ring.

[022] In an embodiment, the filler portion is unassisted by fasteners in retaining it in place. [023] In an embodiment, the filler portion includes an engaging part that engages with an engaging portion of the shell liner to assist in preventing relative rotation therebetween.

[024] In an embodiment, the shell liner includes a geometrical engaging portion that is configured to engage with a corresponding geometrical engaging part on an adjacent component.

[025] In an embodiment, the geometrical engaging portion includes two walls that are laterally offset from one another. In an embodiment, the two walls are laterally offset by a ledge.

[026] In an embodiment, the geometrical engaging portion forms a zigzag shape.

[027] In a further embodiment, the filler portion is rigidly connected to the shell liner. In this further embodiment, the filler portion may be integrally formed with the shell liner. For example, the filler portion may be casted with the shell liner.

[028] In an embodiment, the shell liner includes a chromoly steel. In an embodiment, the hardness of the chromoly steel is between 325HB to 550HB.

[029] In an embodiment, the mill includes one or more metal devices to assist in processing a material. In an embodiment, the one or more metal devices are in the form of balls or rods.

[030] In a second aspect, the present disclosure provides a liner for a mill including: a body including rubber and steel; wherein the body in configured to be connected to an end portion of a mill such that it extends transversely to a shell body that is at least partially enclosed by the end portion.

[031] In an embodiment, the rubber is natural rubber.

[032] In an embodiment, the steel is plain steel.

[033] In an embodiment, the rubber is moulded, at least partially, around the steel.

[034] In an embodiment, the liner includes one or more lifter bars. [035] In an embodiment, the one or more lifter bars includes a plurality of lifter bars that extend transversely to one another.

[036] In an embodiment, the lifter bars are rectangular, trapezoidal or wave-like in shape.

[037] Further features and advantages of the present disclosure will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[038] Various preferred embodiments of the present disclosure will now be described, by way of examples only, with reference to the accompanying figures, in which:

Figure 1 illustrates a section view of a first part of a mill, according to an embodiment of the invention;

Figure 2 illustrates a section view of a second part of the mill, shown in Figure 1 , according to an embodiment of the invention;

Figure 3 illustrates a section view of a filler ring, shown in Figure 1 , according to an embodiment of the invention;

Figure 4 illustrates a section view of a shell liner, shown in Figure 1 , according to an embodiment of the invention;

Figure 5 illustrates a section view of a further shell liner, connected to a filler portion, according to an embodiment of the invention; and

Figure 6 illustrates a section view of an end liner, according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[039] Fig. 1 and Fig. 2 illustrate a section view of a first and second part of a mill 10. The mill 10 includes a mill body 11 , a feed liner 20, a filler portion 30, a shell liner 40 and a discharge liner 60. The mill body 11 includes a plurality of components. The components substantially form a cylindrical body with trunnions at either end. The mill body 1 1 includes a shell body 12. The shell body 12 is substantially cylindrical. The shell body 12 has a plurality of sections 15, 16, 17. The sections 15, 16, 17 are releasably connected together. The sections 15, 16, 17 also include one or more fastening portions to connect to the shell liner 40.

[040] The mill body 1 1 further includes a feed end portion 13 and a discharge end portion 18. The end portions 13, 18 are respectively connected to ends of the shell body 12. The end portions 13, 18 assist in enclosing the cylindrical body formed from the shell body 12. That is, to enclose the cylindrical body, the end portions 13, 18 extend transversely to the wall(s) of the shell body 12. In this regard, the opposed faces of the end portions 13, 18 extend in a transverse manner to the wall(s) of the middle sections 15, 16, 17.

[041] The end portions 13, 18 respectively include rotational connectors. The rotational connectors are in form of trunnions 14 and 19. The trunnions 14, 19 are substantially cylindrical. The trunnions 14, 19 assist in allowing the mill 10 to rotate. That is, the trunnions 14,19 are used as a bearing surface to allow the shell body 12 and end portions 13, 18 to rotate. The trunnions 14, 19 also act as an inlet and outlet for the mill 10. Accordingly, material enters through the trunnion 14 and, after crushing/grinding, exits through trunnion 19.

[042] The feed liner 20 is connected to the feed end portion 13 of the mill body 11 . That is, the feed liner 20 is bolted to the feed end portion 13. The feed liner 20 is formed from a rubber and steel composition. The rubber is natural rubber. The steel is plain steel (eg, a low carbon steel). The rubber is moulded around the steel to form the liner. In a non-obvious manner, the rubber and steel composite reduce the liner weight (improving grinding efficiency) and increase the liner service life. Normally, steel liners are implemented in these area as harder materials are generally thought to have a longer service life.

[043] The feed liner 20 extends transversely to the shell body 12. The feed liner 20 includes an inner feed liner 22 and an outer feed liner 24. The inner feed liner 22 is located closest to the trunnion 14. The outer feed liner 24 is located closest to the filler portion 30. The feed liner 20 includes a plurality of feed liner lifter bars 26. The feed liner lifter bars 26 are arranged in an annular array, inward from the shell body 12. That is, the lifter bars 26 extend transversely to one another in a direction towards the trunnion 14. The lifter bars 26 are connected to a plate. The plate thickness may be between 50mm to 200mm and, preferably, is between 100mm to 120mm. The lifter bars 26 may be 200mm to 400mm in height and, preferably, 250mm to 300mm in this embodiment. The lifter bars 26 are separated in a manner that leaves valleys therebetween. The shape of the lifter bars 26 can be (amongst other things) rectangular, trapezoidal or wave-like in shape. [044] One filler portion 30 is installed between the feed liner 20 and shell liner 30. Another filler portion 30 is also installed between the shell liner 40 and the discharge liner 60. The filler portions 30 are substantially circular and form a ring. The filler portions 30 include a Cr-Mo, or chromoly, steel (steel alloy containing chromium and molybdenum) . This assists in avoiding, for example, bolt breakage in the shell liner 40. That is, the filler portions 30 are hard and difficult to deform. This provides strong horizontal support to the shell liner 40. As such, relative motion between the shell liner 40 and its associated bolts is minimised by the filler portions 30. The Cr- Mo steel has a hardness between 325-550HB in this embodiment. As detailed below, the filler portions 30 are not fixed by, for example, bolts. The filler portions 30 rely on geometry to connect to adjacent components.

[045] As shown further in Fig .3 , the filler portions 30 includes an engaging part 32 and a geometrical engaging part 34. The engaging part 32 includes one or more protrusions that are configured to engage with the shell liner 40. The protrusions extend away from a side wall of the filler portion 30. The protrusions are substantially convex. The protrusions assists in preventing relative motion between the filler portions 30 and the shell liner 40. The geometrical engaging part 32 includes two walls that are offset from one another with a ledge therebetween. That is, the geometrical engaging part 32 forms a zigzag shape. The geometrical engaging part 32 therefore assists in avoiding a vortex flow which can lead to lead to excessive wear of the gap between the filler portions 30 and the shell liner 40.

[046] The shell liner 40 is connected to the shell body 12. That is, the shell liner 40 is releasably connected to the shell body 12 with one or more fasteners. The shell liner 40 includes a plurality of sections. This assists with managing maintenance costs as sections having higher wear / breakage areas can be replaced more regularly (cf. replacing the complete liner). The shell liner 40 includes Cr-Mo steel. The Cr may vary between 1% to 5%. The hardness of the steel may range between 325HB to 550HB.

[047] In this embodiment, the shell liner 40 includes a first section 41 , a second section 42, a third section 43, a fourth section 44, a fifth section 45 and an end section 46. Overall, there are 24 rows of liners in these six sections. The shell liner 40 includes a plurality of lifter bars 52. The lifter bars 52 are circumferentially spaced apart around the shell body 12. The lifter bars 52 extend longitudinally along the mill 10. The lifter bars 52 (like the lifter bars 26) are configured to capture material between each bar 52 and lift it to a height to be dropped. This assists with breaking / grinding the material. [048] In this embodiment, the lifter bars 52 include different height bars. That is, the lifter bars include a low lifter bar 54 and a high lifter bar 55. The high lifter bar 55 extends further away from a backing plate compared to the low lifter bar 54. The backing plate is approximately 50mm to 100mm thick and, preferably, 60mm to 90mm thick. The height of the high lifter bars 55 may vary between 200mm to 100mm and, preferably, is between 150mm to 170mm. The height of the low lifter bars 54 may vary between 150mm to 100mm and, preferably is between 135mm to 125mm. The low lifter bar 54 and the high lifter bar 55 are located adjacent to one another. The lifter bars 54, 55 (like embodiments of the lifter bars 26) are curved in shape.

[049] The sections 41 -46 are connected together using engaging portions 56 and geometrical engaging portions 58. The engaging portions 56, shown in Fig. 4, are in the form receptacles. The receptacles are configured to receive, for example, the engaging parts 32. It will also be appreciated that, whilst the sections 41 -46 will have the engaging portions 56 on one end, engaging parts (similar to engaging parts 32) will be located on the other end. This allows the sections 41-46 to be connected together in a manner that reduces the relative motion therebetween.

[050] The geometrical engaging portion 58 complements the geometrical engaging part 34. In this regard, the geometrical engaging portion 58 has a zigzag-like shape. That is, it has two walls laterally offset from one another with a ledge therebetween. The ledge extends transversely to the walls. The shape of the zigzag portions reduces the relative motion of the shell sections 41-46, avoiding vortex flow which can lead to excessive wear of the gaps between various sections of the shell liner 40 and the filler portions 30. To this end, it would be appreciated that each section 41 -46 of the shell liner 40 would have a geometrical engaging part on an opposing end (similar to geometrical engaging part 34) in order engage with an adjacent section's geometrical engaging portion 58.

[051] Fig. 5 illustrates a further embodiment of a filler portion 30a and a shell liner 40a. The filler portion 30a and shell liner 40a are substantially the same as filler portion 30 and shell liner 40. However, in this embodiment, the filler portion 30a is casted together with shell liner 40a. In other words, the filler portion 30a and the shell liner 40a are integrally formed. The filler portions 30a can be located on either end of the shell liner 40a. The integrally formed product may assist in installation processes.

[052] The discharge liner 60 is connected to the discharge end portion 18. That is, the discharge liner 60 is bolted to the discharge end portion 18. The discharge liner 60 is substantially similar to the feed liner 20. In this regard, the discharge liner 60 includes a rubber / steel composite. The discharge liner 60 extends transversely to the shell body 12. The discharge liner 60 includes an inner discharge liner 62 and an outer discharge liner 64. The inner discharge liner 62 is located closest to the trunnion 19. The outer discharge liner 64 is located closest to the filler portion 30.

[053] Like the feed liner 20, the discharge liner 60 includes a plurality of discharge liner lifter bars 66. The lifter bars 66 are substantially similar to the lifter bars 26. The lifter bars 66 extend transversely to one another in a direction towards the trunnion 19. The lifter bars 66 therefore extend radially along the discharge end portion 18. The lifter bars 66 are separated in a manner that leaves valleys therebetween (as they extend away from a plate). The shape of the lifter bars 66 can be (amongst other things) rectangular, trapezoidal or wave-like in shape.

[054] Fig. 6 illustrates a close up section view of discharge liner 60. As further detailed in Fig. 6, the discharge liner 60 includes steel plates 68 that extend around a lower outer perimeter of the outer discharge liner 64. These plates 68 may also be included in the feed liner 20. The plates 68 assist in minimising deformation in the rubber moulded around the other areas of the discharge liner 60. This also minimises wear in associated regions due to penetration of metallic balls through, for example, a gap between the filler portion 30 and least one of the feed liner 20 or the discharge liner 60. The plates 68 are uncovered by the rubber.

[055] During use, material enters through the hollow portion of the trunnion 14 into the shell body 12. The mill body 11 rotates using the trunnions 14, 19 as rotational parts. This causes the material to be lifted and dropped, with the assistance of the lifter bars 26, 52, 66, to cause breaking and grinding of the material. Metal devices, including balls and rods, may be added in the mill body 11 to assist in refining the material. Due to (amongst other things) the shape of the liners 20, 40, 60, the material is guided along the mill 10 towards the trunnion 19 as it is refined. The refined material leaves through the opening in the trunnion 19 in order to be processed/collected further downstream.

[056] The mill 10 provides a number of advantages. For example, the feed and discharge liners 20, 60 use a rubber/steel composite material that reduces the liner weight, improving grinding efficiency. The filler portions 30 use a Cr-Mo steel that, for instance, assists in avoiding the occurrence of bolt breakage along the shell liner 40. The use the tongue and groove connecting system (including 32, 56) avoids the relative motion between (for example) the filler portions 30 and shell liners 40. The zigzag shape between the sections 41-46 and the filler portions 30 also assist in avoiding a vortex flow which can lead to an excessive wear of the gap therebetween. [057] The plates 68, around the outer perimeter (or rim) of the liners 20, 60, also minimise the deformation of the rubber associated with the liners 20, 60. The plates 68 also minimise wear, particularly for the shell body 12, improving mill operation safety.

[058] In this specification, adjectives such as left and right, top and bottom, hot and cold, first and second, and the like may be used to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where context permits, reference to a component, an integer or step (or the alike) is not to be construed as being limited to only one of that component, integer, or step, but rather could be one or more of that component, integer or step.

[059] In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’, ‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

[060] The above description relating to embodiments of the present disclosure is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the disclosure to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present disclosure will be apparent to those skilled in the art from the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The present disclosure is intended to embrace all modifications, alternatives, and variations that have been discussed herein, and other embodiments that fall within the spirit and scope of the above description.

Claims (25)

1. A mill including: a mill body having: a shell body; a feed end portion connected to the shell body to at least partly enclose one end of the shell body; a discharge end portion connected to the shell to at least partly enclose another end of the shell body; a shell liner connected to the shell body; a feed liner connected to the feed end portion; and a discharge liner connected to the discharge end portion, wherein the feed liner and the discharge liner extend transversely to the shell liner.

2. The mill of claim 1 , wherein at least one of the feed liner or the discharge liner include steel and rubber.

3. The mill of claim 2, wherein the rubber is moulded, at least partially, around the steel.

4. The mill of any one of claims 1 to 3, wherein at least one of the shell liner, feed liner or the discharge liner include one or more lifter bars.

5. The mill of claim 4, wherein the one or more lifter bars include lifter bars of different height.

6. The mill of claim 4 or 5, wherein the one or more lifter bars include a plurality of lifter bars associated with the feed liner or the discharge liner, the plurality of lifter bars extending transversely to one another.

7. The mill of claim 6, wherein the plurality of lifter bars extend radially towards a trunnion.

8. The mill of any one of the preceding claims, wherein at least one of the feed liner or the discharge liner includes one or more steel plates extending around part of their outer perimeter.

9. The mill of any one of the preceding claims, wherein a filler portion is located between the shell liner and at least one of the feed liner or the discharge liner.

10. The mill of claim 9 when dependent on claim 8, wherein the one or more steel plates extend around part of the perimeter that is adjacent to the filler portion.

11 . The mill of claim 9 or 10, wherein the filler portion is substantially in the form of a ring.

12. The mill of any one of claims 9 to 11 , wherein the filler portion includes a chromoly steel.

13. The mill of claim 12, wherein the hardness of the chromoly steel of the filler portion is between 325HB to 550HB.

14. The mill of any one of claims 9 to 13, wherein the filler portion includes an engaging part that engages with an engaging portion of the shell liner to assist in preventing relative rotation therebetween.

15. The mill of any one of claims 9 to 13, wherein the filler portion is integrally formed with the shell liner.

16. The mill of any one of the preceding claims, wherein the shell liner includes a geometrical engaging portion that is configured to engage with a corresponding geometrical engaging part on an adjacent component.

17. The mill of claim 16, wherein the geometrical engaging portion includes two walls that are laterally offset from one another.

18. The mill of claim 17, wherein the two walls are laterally offset by a ledge.

19. The mill of any one of claims 16 to 18, wherein the geometrical engaging portion forms a zigzag shape.

20. The mill of any one of the preceding claims, wherein the shell liner includes a chromoly steel.

21 . The mill of claim 20, wherein the hardness of the chromoly steel of the shell liner is between 325HB to 550HB.

22. The mill of any one of the preceding claims, wherein the mill includes one or more metal balls or rods to assist in processing a material.

23. A liner for a mill including: a body including rubber and steel, wherein the body in configured to be connected to an end portion of a mill such that it extends transversely to a shell body that is at least partially enclosed by the end portion.

24. The liner of claim 23, wherein the liner includes one or more lifter bars.

25. The liner of claim 24, wherein the one or more lifter bars includes a plurality of lifter bars that extend transversely to one another.