Patent Application
20240269685
The present disclosure relates to a system and a method for mounting a liner element to a mill shell of a mill, such as a tumbling mill.
Liner elements for mills, such as tumbling mills, often have dedicated lifting points for placement on the mill wall using a mill reline machine grapple. However, these lifting points are destroyed during mill operation. Consequently, spent liners must be ‘knocked-in’, a process where the liners are dislodged from the wall using a bolt hammer or similar tool and land on the mill charge below. Traditional lifting techniques are then used to pick up and remove the spent liners from the mill. These traditional lifting techniques require trained personnel to work alongside the mill reline machine to install lifting equipment, attach this equipment to the mill reline machine lifting points and finally, guide the load during the lifting process. To reduce the overall need for personnel, and thus provide a more efficient relining, there is a need for an improved method and system for allowing mill reline machines to use their grapple to both place new liners and remove spent liners directly from the mill wall with no assistance from personnel inside the mill.
It is an object to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination. These and other objects are at least partly met by the invention as defined in the independent claims. Preferred embodiments are set out in the dependent claims.
According to a first aspect there is provided a system for mounting a liner element to a mill shell of a mill, said liner element having a back side arranged to face the mill shell and a front side arranged to face an interior of the mill, when mounted on the mill shell, the system comprising:
The system may be advantageous as it allows mounting new liner elements as well as removing worn our liner elements using a mill reline machine without the need for personnel being present within the mill. The unassisted pick up of liners directly from the mill wall provided by the present inventive concept is an important step in making mill relining more efficient and promotes greater autonomy for the relining process. Identifying and utilizing an interface on both new and spent liners is the key step in achieving unassisted relining. The system of the disclosure may provide this interface by utilizing the bolt heads as lifting portions. Once the liner element has been mounted in its intended position, the one or more liner interface guide elements can be detached from its respective fastening bolt and re-used for other liner elements. A further advantage of the system is that the one or more liner interface guide elements provide guiding portions for facilitating the mounting process. The guide portions engage with the mill shell through-holes to guide the liner elements into its correct position, i.e. the mounting position. A further advantage of the system is that, once the liner element has been mounted in its mounting position, the guide portions at least partly protrude outside of the mill shell. Parts of the guide portions are therefore made accessible from the outside and may be engaged e.g. by personnel to correctly position the fastening bolts in the liner element through-holes and also facilitates easy removal of the liner interface guide elements from the fastening bolts to which they are attached. A yet further benefit of the system is that it effectively removes the need for using customised reline jigs. The reline machine grapple may be structured and arranged to engage with the lifting portions directly using a single grapple design applicable for both mounting and demounting the liner element to the mill shell.
Each fastening bolt and its associated liner interface guide element are structured and arranged to be attached to each other so as to form a common linearly extending structure. This implies that, when attached to each other, the fastening bolt and its associated liner interface guide element both extend along a common axis, namely the axis aligned along a longitudinal extension of the liner element through-hole. The locking portion of the liner interface guide element has the same basic functionality as the bolt head of the fastening bolt, namely, to engage with the liner element to prevent further movement into the liner element through-hole. This implies that the liner interface guide element and the fastening bolt attached thereto does not have to be rigidly attached to the liner element. The locking functionality of the inventive concept may thus allow certain movement within the liner element through-hole. This implies that the fastening bolts are displacably coupled to the liner element. This have the advantage that, once the liner interface guide element has been released from its associated fastening bolt, each of said items are removable from the liner element without the need to exert any force, such as is needed for alternative solutions where the elements are driven into a locking, or retaining, engagement with the liner element by use of force.
The fastener may be a fastening element, such as a fastening nut. Alternatively, it may be another kind of fastening element such as a snap fit fastener.
According to some embodiments, the system further comprises locking means arranged to engage with the mill shell and said externally accessible engagement portions for allowing temporarily locking the liner element to the mill shell prior to securing the liner element using said one or more fastening bolts and their associated fasteners.
The locking means allowing to temporarily lock the liner with respect to the mill shell may be advantageous as it may prevent a liner element from accidentally falling down during mounting. The locking means thus provide an extra security during the mounting process. However, the locking engagement achieved by the locking means should not be construed as a fixed attachment which forces the liner element to stay in the mounting position at all times. Due to the geometry of the fastening bolts and their associated liner interface guide elements, the liner element may leave the mounting position to be displaced a certain distance into the interior of the mill, until, being prevented from further displacement by the locking means.
According to some embodiments, the locking means is defined by a locking through-hole formed in each engagement portion, and an associated locking element arranged to be received in said locking through-hole. The locking through-hole and locking element is a relatively simple way to achieve the temporary locking of the liner element with respect to the mill shell. A locking element may be a simple straight pin or bolt with a head. The locking element may alternatively be at least partly curved. One such locking element is sometimes called Beta Pins or R-Clips due to their R form. These locking elements may be advantageous as they are shaped to clamp the element to which they are pinned, thereby reducing the risk that they accidentally move out of position and leaves the liner interface guide element. As readily appreciated by the person skilled in the art, there are many alternative locking means known in the art which could be used to act instead of the locking element and the through-hole.
According to some embodiments, the guide portion of each liner interface guide element is at least partly tapered. This may be advantageous as it facilitates entering the mill shell through-holes with the guide elements during mounting of the liner element.
According to some embodiments, each fastening bolt and its associated liner interface guide element are attachable to each other by means of threaded engagement. The threaded engagement is a preferred fastening means as it is reliable.
According to some embodiments, each fastening bolt comprises a liner interface guide element attachment portion at an end of the bolt body for providing said threaded engagement, and a fastener attachment portion for engagement with the fastener. Using separate attachment portions for the fasteners and for the liner interface guide elements may have several advantages. Firstly, it allows using fastener attachment portions which fills the maximum available through-hole diameter, which is beneficial as it aids in providing a stronger mount of the liner element and reduces the risk of the liner element moving sideways due to a large bolt clearance. Secondly, it allows tailoring the properties of the threaded engagement to the specific need at hand. The mechanical strain exerted on the fastener attachment portion during mill operation may be vastly different from the mechanical strain exerted on the liner interface guide element attachment portion during mounting and removal of liner elements. Another advantage is that it allows less geometrical constraints for the liner interface guide elements.
According to some embodiments, the liner interface guide element attachment portion comprises a male thread and wherein the associated liner interface guide element comprises a female thread arranged to be received in the male thread. This implies that the fastener attachment portion may be disposed in between the bolt head and the liner interface guide element attachment portion. The opposite geometry is however also conceivable. In other words, the liner interface guide element attachment portion may comprise a female thread and wherein the associated liner interface guide element may comprise a male thread arranged to be received in the female thread. This implies that the fastener attachment portion may be disposed at the same axial position as the liner interface guide element attachment portion. The fastener attachment portion may be a male thread defined at an outside of the fastening bolt whereas the liner interface guide element attachment portion may be defined by a female thread formed within an interior of the fastening bolt.
According to some embodiments, a cross-sectional dimension of the liner interface guide element attachment portion is smaller than a cross-sectional dimension of the bolt body, and wherein a cross-sectional dimension of the threaded attachment portion is substantially equal to a cross-sectional dimension of the bolt body. This may be advantageous as it allows the shape that together is defined by the fastening bolt and the liner interface guide element to have substantially the same cross section in an intermediate region thereof, thus preventing accidental jams and facilitates an easy displacement of the fastening bolt and its associated attached liner interface guide element between different positions within the liner element through-hole.
According to some embodiments, the bolt head of each fastening bolt comprises an outer wear plug structured and arranged to prevent material from entering the associated liner interface through-hole during use of the mill. The outer wear plug may be advantageous as it fills the entrance opening of the liner element through-hole during mill operation thereby reducing the likelihood of ore and balls lodging in the through-hole. The outer wear plug may be dimensioned to the expected thickness of the liner when it is replaced. The outer wear plug may be made from a resilient wear-resistant material such as rubber or polyurethane. The outer wear plug may be structured and arranged to completely fill the opening of the liner element through hole on the front side of the liner element when attached. This may reduce the risk of material getting stuck in recesses otherwise formed at such openings. It may also prevent damage, such as by peeling, to the openings due to wear during operation.
According to some embodiments, the system further comprises one or more collars each structured and arranged to be disposed around the bolt body of the fastening bolt inside the mill shell through-hole. The collars may be advantageous as they increase overall stability of the mount by compensating for the mill shell through-holes being larger than the liner element through-holes, a requirement for using the system of the inventive concept, since the liner interface guide elements would otherwise not fit inside the mill shell through-holes.
According to a second aspect there is provided a liner assembly for a mill comprising:
According to some embodiments, the waist portion is disposed in vicinity of the back side of the liner element and the part of the liner element through-hole extending from the waist portion to the front side is tapered. This may be advantageous as it makes it easier to knock the fastening bolt free from the liner element during a removal thereof.
A mill may also be provided, said mill comprising a mill shell presenting a plurality of mill shell through-holes for allowing mounting a plurality of liner elements on an inside thereof; and
According to a third aspect there is provided a method for mounting a liner element to a mill shell of a mill, said liner element having a back side arranged to face the mill shell when mounted, and a front side arranged to face an interior of the mill, the method comprising:
According to some embodiments, the method further comprises arranging said one or more fastening bolts and their associated one or more liner interface guide elements attached thereto such that their bolt heads protrudes out from the front side of the liner element to define lifting portions, and lifting the liner element by engaging the lifting tool with said lifting portions.
According to some embodiments, the method further comprises temporarily locking the liner element to the mill shell by activating locking means which provides an engagement between the engagement portions and the mill shell prior to securing the liner element using said associated fasteners.
Effects and features of the second and third aspects are largely analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect and third aspects. It is further noted that the inventive concepts relate to all possible combinations of features unless explicitly stated otherwise.
A further scope of applicability of the present disclosure will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.
Hence, it is to be understood that this disclosure is not limited to the particular component parts of the device described or steps of the methods described as such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It must be noted that, as used in the specification and the appended claim, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to “a unit” or “the unit” may include several devices, and the like. Furthermore, the words “comprising”, “including”, “containing” and similar wordings does not exclude other elements or steps.
The disclosure will by way of example be described in more detail with reference to the appended drawings, which shows presently preferred embodiments of the disclosure.
The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the disclosure to the skilled person.
Tumbling mills comprises large rotary grinding drums into which material to be grinded are input. As a result from abrasive as well as impact wear, the walls of the drum, herein referred to as the mill shell, needs to be equipped with a wear resistant lining. Such lining often comprises a plurality of liner elements which are mounted together to form a single inner wear surface interacting with the material in the interior of the mill. Once the lining is worn out, it will need to be replaced. For this purpose, mill reline machines are typically used to replace one or more liner elements. The present inventive concept has been developed to meet requirements in this area. The inventive concept relates to a system and a method for mounting a liner element to a mill shell of a mill, such as a tumbling mill. Before describing the method, the different parts of the system will be described in detail with reference to
Also illustrated in
The fastening bolt 130 and an associated liner interface guide element 110 are structured and arranged to be attached to each other, thereby forming a common elongated element. This is illustrated in
Turning now to
Turning now to
In a first step, one or more fastening bolts 130 (in the example embodiment: three fastening bolts 130) are inserted into associated liner element through-holes 16 of the liner element 10 from the front side 14 thereof. Then, associated liner interface guide elements 110 are attached to each of the fastening bolts 130. As already explained, this will lock the fastening bolts 130 and the liner interface guide elements 110 to their respective liner element through-holes 16 as a result from the relative cross-sectional dimensions discussed earlier. Each liner interface guide element 110 protrude out from the back side 12 of the liner element 10 to define an associated guide portion 112.
In a next step, the liner element 10 is lifted by means of a lifting tool 60 into a position with respect to the mill shell 2 at which the liner interface guide elements 110 axially coincide with associated mill shell through-holes 2. This is the position illustrated in
In a next step, the liner element 10 is displaced, by means of the lifting tool 60, into the mounting position at which the liner element 10 is in abutment with the mill shell 2. This is achieved by allowing the guide portions 112 of the liner interface guide elements 110 to penetrate into the mill shell through-holes 4 as indicated in
In a next optional step, locking means 150 are activated for temporarily locking the liner element 10 to the mill shell 2. The locking means 150 thus provides an engagement between the engagement portions 118 and the mill shell 2 prior to (permanently) securing the liner element 10 using said associated fasteners 140. The locking means 150 allows to temporarily lock the liner element 10 with respect to the mill shell 2 may be advantageous as it may prevent the liner element 10 from accidentally falling down during mounting thereof. The locking means 150 may thus provide an extra security during the mounting process. However, as can be deduced from analysing the relative geometry of the liner interface guide elements 110 and their associated fastening bolts 130 in relation to the liner element 10 and the mill shell 2 in
As illustrated in
In a next step, each liner interface guide element 110 and its associated fastening bolt 130 are displaced with respect to the liner element 10 to a fastening position at which the bolt head 132 engages with the liner element 10. This step is illustrated in
Once the liner interface guide element 110 has been removed from the fastening bolt 130, its fastener attachment portion 138 will be revealed, as illustrated in
As readily appreciated by the person skilled in the art it is not essential that the number of liner interface guide elements 110 and fastening bolts 130 are equal. To fasten a liner element to a mill shell, two, four or even more fastening bolts 130 may be needed dependent on the liner element dimensions, the dimensions of the fastening bolts, and the physical requirements for the mill. However, for guiding a liner element to a mounting position on the mill shell, it may suffice with only one liner interface guide element 110. However, two liner interface guide elements 110 are preferred to provide better stability during the lift procedure when using the bolt heads as lifting points, as well as for providing more accurate guiding of the liner element towards the mounting position. For embodiments of the inventive concept where the liner element 10 is lifted by means of the bolt heads 132 of the fastening bolts 130, it is essential that those fastening bolts 130 that serves as lifting points are all attached to associated liner interface guide elements 110, or to any other element having a larger cross-sectional dimension than the minimum cross-sectional dimension D3 of the waist portion 18 of the liner element through-hole 16, so as to prevent the fastening bolt 130 from escaping said liner element through-hole 16. It is however preferred to attach liner interface guide elements 110 to all fastening bolts 130, as it reduces the risk that a fastening bolt 130 accidentally falls out from its liner element through-hole 16 during the mounting process.
As readily appreciated by the person skilled in the art, the same basic procedure may be used when removing a worn-out liner element from the mill, although in reverse. First, one or more fasteners 140, here illustrated as fastening nuts 140) are removed from their associated fastening bolts 130. Typically, at least one fastener 140 is left in place starting with removal of the other ones. This is especially preferred for embodiments where the mill reline machine are to lift the liner element 10 by the bolt heads 132, as there may for those embodiments be no other way to engage the lifting tool 60 of the mill reline machine with the liner element 10 prior to unfastening at least one of the fasteners 140. Engaging the lifting tool 60 with the liner element prior to finishing the unmounting process is preferred as it reduces the risk that the liner element 10 falls down into the mill prior to being properly engaged by the lifting tool 60. One or more liner interface guide elements 110 are then attached to the unsecured fastening bolts. Optionally, locking means 150 are activated to temporarily lock the liner element 10 to the mill shell 2. At least one fastening bolt 130 having an attached liner interface guide element 110 is then displaced, typically by using a bolt hammer, such that the bolt head 132 protrudes out from the front side 14 of the liner element 10 to define lifting points for the lifting tool 60. The mill reline machine can then be operated to manoeuvre the lifting tool 60 to engage with lifting points of the at least one fastening bolt 130. Alternatively, the mill reline machine can instead be operated to manoeuvre the lifting tool 60 to engage with alternative lifting points on the liner element, e.g. of conventional type. Once the liner element 10 is held firmly in position against the mill shell 2 by the mill reline machine, the remaining fasteners 140 may be removed. Optionally, associated liner interface guide elements 110 may be attached to the last fastening bolts 130. Finally, when all fasteners 140 have been removed, the mill reline machine may manoeuvre the lifting tool 60 to remove the liner element from the mill shell 2.
The person skilled in the art realizes that the present disclosure by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21181262.3 | Jun 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/065702 | 6/9/2022 | WO |
