SYSTEM AND METHOD FOR MOUNTING A LINER ELEMENT TO A MILL SHELL OF A MILL

A system and method for mounting a liner element to a mill shell of a mill. The system includes one or more fastening bolts, and one or more associated liner interface guide elements each having a locking portion having a cross-sectional dimension larger than a cross-sectional dimension of a bolt body of the fastening bolts. Each fastening bolt and an associated liner interface guide element are structured and arranged to be attached to each other such that, when inserted into the liner element through-hole, the liner interface guide element, by means of the locking portion, locks the fastening bolt to the liner element and protrudes out from the back side thereof to define a guide portion. The guid portion is arranged to penetrate into an associated mill shell through-hole thereby guiding the liner element into a mounting position at which the liner element is in abutment with the mill shell.

FIELD OF THE DISCLOSURE

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.

BACKGROUND ART

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.

SUMMARY

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:one or more fastening bolts each having a bolt head and a bolt body extending from the bolt head, each fastening bolt being structured and arranged to be inserted into an associated liner element through-hole from the front side thereof and to be secured from outside the mill shell using an associated fastener; andone or more associated liner interface guide elements each having a locking portion having a cross-sectional dimension being larger than a cross-sectional dimension of the bolt body of the one or more fastening bolts; andwherein each fastening bolt and an associated liner interface guide element are structured and arranged to be attached to each other such that, when inserted into said associated liner element through-hole, said associated liner interface guide element, by means of the locking portion, locks the fastening bolt to the liner element and protrudes out from the back side thereof to define a guide portion which, during mounting of the liner element on the mill shell, is arranged to penetrate into an associated mill shell through-hole thereby guiding the liner element into a mounting position at which the liner element is in abutment with the mill shell, and at which mounting position the guide portion at least partly protrudes out from the mill shell on an outside thereof so as to present an externally accessible engagement portion.

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:a system according to the first aspect; anda 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, wherein the liner element comprises one or more liner element through-holes each extending from the back side to the front side and comprising a respective waist portion which presents said minimum cross-sectional dimension of the liner element through-hole.

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; andat least one liner assembly according to the third aspect;wherein a cross-sectional dimension of each of the mill shell through-holes are larger than the cross-sectional dimension of the locking portion of each liner interface guide element of said system.

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:a) inserting one or more fastening bolts into associated liner element through-holes of the liner element from the front side thereof, each fastening bolt having a bolt head and a bolt body extending out from the bolt head;b) to each of said one or more fastening bolts, attaching an associated liner interface guide element having a locking portion having a maximum cross-sectional dimension being larger than a cross-sectional dimension of the bolt body of the one or more fastening bolts such that said associated liner interface guide element locks the fastening bolt to the liner element and protrude out from the back side of the liner element to define an associated guide portion;c) lifting by means of a lifting tool the liner element into a position with respect to the mill shell at which the one or more liner interface guide elements axially coincide with one or more associated mill shell through-holes;d) displacing by means of the lifting tool the liner element into a mounting position at which the liner element is in abutment with the mill shell by allowing said associated guide portions to penetrate into said one or more associated mill shell through-holes, thereby guiding the liner element into said mounting position, and at which mounting position each guide portion at least partly protrude out from the mill shell on the outside thereof so as to present an externally accessible engagement portion;e) displacing, by engaging said engagement portion, each liner interface guide element and its associated fastening bolt with respect to the liner element to a fastening position at which the bolt head engages with the liner element;f) removing each of the one or more liner interface guide elements from its associated fastening bolt;g) securing each fastening bolt from outside the mill shell using an associated fastener.

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.

DETAILED DESCRIPTION

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 toFIG.1.

FIG.1shows to the left a fastening bolt130. The fastening bolt130is structured and arranged to be inserted into an associated liner element through-hole16of a liner element10from the front side14thereof and to be secured from outside the mill shell2using an associated fastener, fastening bolt140. This will be described later with reference toFIG.2. As best illustrated inFIG.1, the fastening bolt130has a bolt head132and a bolt body134extending from the bolt head132. The bolt head132has a rotationally asymmetric cross section (not shown) structured and arranged to fit into complementary shaped liner element through-holes16of the liner element10. Such bolt heads having rotationally asymmetric cross sections are well known in the art and are used to prevent the bolts from rotating in relation to the through-holes when engaging and rotating a fastening means, such as a fastener mounted thereon. The bolt head132further present a frustoconical rim135which is arranged to press a waist portion18of the liner element10towards the mill shell2, as will be described in more detail later. The bolt head132further comprises an outer wear plug133structured and arranged to prevent material from entering the associated liner interface through-hole16during use of the mill. The outer wear plug133is at least partly tapered for facilitating removal of the fastening bolt130from a used liner element. The outer wear plug133may be made from a resilient wear-resistant material such as rubber or polyurethane. Although not shown inFIGS.3A-F, the outer wear plug may alternatively 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 formed at such openings. It may also prevent damage, such as by peeling, to the openings due to wear during operation. The fastening bolt130further comprises two separate threaded attachment portions: a fastener attachment portion138, and a liner interface guide element attachment portion136. As can be seen inFIG.1A, the liner interface guide element attachment portion136is disposed at the end of the bolt body134and has a cross-sectional dimension W1being smaller than a cross-sectional dimension D1of the bolt body134disposed adjacent thereto. For the example embodiment, both the liner interface guide element attachment portion136and the fastener attachment portion138presents male threads. However, as readily appreciated by the person skilled in the art, it is also conceivable with the inverted geometry, i.e. providing the fastening bolt130with a female thread and the liner interface guide element110with a male thread.

Also illustrated inFIG.1Abut to the right is a liner interface guide element110according to an example embodiment. The liner interface guide element110has an elongated extension and presents at one end thereof a guide portion112and at another end thereof a threaded attachment portion116. The cross-sectional dimension W2of the threaded attachment portion116is substantially the same as the cross-sectional dimension D1of the bolt body134except for the guide portion112which has a larger cross-sectional dimension. The maximum cross-sectional dimension D2of the liner interface guide element110is located where the guide portion112starts and defines a locking portion111. The relevance of the locking portion111and its dimensions will be explained later. The liner interface guide element110further comprises a tool-connecting portion119disposed between the threaded attachment portion116and the guide portion112. The purpose of the tool-connecting portion119is to facilitate engagement with a tool, such as a wrench or spanner, to rotate the liner interface guide element110during an attachment or detachment thereof. The tool-connecting portion119may be embodied in different ways. For example, it may be embodied by one or more machined flats in its outer circumferential surface. A preferred embodiment is to machine six flats so as to provide a tool-connecting portion119having a hexagonal cross section. A locking through-hole152is presented in the guide portion112of the liner interface guide element110at the outer end thereof. The functionality of the locking through-hole152will be described later.

The fastening bolt130and an associated liner interface guide element110are structured and arranged to be attached to each other, thereby forming a common elongated element. This is illustrated inFIG.1B. The attachment is obtained by engaging the liner interface guide element attachment portion136of the fastening bolts130with the threaded attachment portion116of the liner interface guide element110. In the example embodiment, the liner interface guide element attachment portion136comprises a male thread137and the associated liner interface guide element110comprises a female thread117arranged to be received in the male thread137. The female thread137is disposed within the threaded attachment portion116. As can be seen inFIG.1B, a cross-sectional dimension W2of the threaded attachment portion116of the liner interface guide element110is substantially equal to a cross-sectional dimension D1of the bolt body134. However, it is clear that the locking portion111has a maximum cross-sectional dimension D2being larger than a cross-sectional dimension D1of the bolt body134of the one or more fastening bolts130.

Turning now toFIG.2A-C, the fastening bolt130and the liner interface guide element110when attached to each other will be illustrated together with the geometry of the liner element through-hole16and the mill shell through-hole4, respectively. As can be seen inFIG.2A, the liner element through-hole16extends from the back side12to the front side14of the liner element10and comprises a waist portion18which presents a minimum cross-sectional dimension D3of the liner element through-hole16. The waist portion18is disposed in vicinity of the back side12of the liner element10and the part of the liner element through-hole16which extends from the waist portion18to the front side14is tapered. To the right-hand side inFIG.2Aa portion of the mill shell2is illustrated in cross sectional view to illustrate a mill shell through-hole4. InFIG.2A, the liner element10is located in relation to the mill shell2such that the liner element through-hole16axially coincide with the mill shell through-hole4and the liner element10is in abutment with the mill shell2. This is referred to herein as the mounting position and is the position at which the liner element10will be located when fastened and subsequently used during operation of the mill. As can be seen inFIG.2A, the cross-sectional dimension D4of the mill shell through-hole4is larger than the minimum cross-sectional dimension D3of the liner element through-hole16, i.e. the minimum cross-sectional dimension D3of the waist portion18. This is an important prerequisite for using the system and method of the inventive concept, as will be understood in what follows.

FIGS.2Band C illustrates the same cross-sectional view of the through-holes4,16asFIG.2A, but here the fastening bolt130and the liner interface guide element110attached thereto are illustrated in their intended positions inside the through-holes4,16. Focusing now primarily on geometry, leaving the functionality to later, it can be clearly seen inFIG.2Bat a first end position, the frustoconical rim135of the bolt head132engages with the complementary shaped waist portion18of the liner element through-hole16, thus effectively preventing further movement of the fastening bolt130in the direction towards the mill shell2. Turning toFIG.2C, it can be clearly seen that at a second end position, the locking portion111of the liner interface guide element110engages with the waist portion18from the other direction, thus effectively preventing further movement in the direction away from the mill shell2. Thus, the geometry is such that, once attached to each other when at least one of them has been arranged inside a liner element through-hole16, the fastening bolt130and the liner interface guide element110attached thereto cannot leave the liner element10and are thus locked thereto. This implies that at neither end position they will be fixedly, or rigidly, attached to the liner element10, such as could be achieved by driving the elements into a jamming engagement with the liner element. At all times, they are displacably coupled thereto. They may however not leave the liner element10, i.e. they are locked with respect to the liner element10. The only way to remove the fastening bolt130and/or the liner interface guide element110, is to separate them from each other and remove them separately from the front side14, and the back side12, respectively.FIG.2Calso clearly illustrates that the cross-sectional dimension D4of the mill shell through-hole4is larger than the maximum cross-sectional dimension D2of the locking portion111of the liner interface guide element110. This allows for introducing the liner interface guide element110through the mill shell through-hole4during mounting and dismounting, as will be described in what follows.

Turning now toFIGS.3A-F, a method for mounting a liner element10to a mill shell2using the already described system will be described in detail.

In a first step, one or more fastening bolts130(in the example embodiment: three fastening bolts130) are inserted into associated liner element through-holes16of the liner element10from the front side14thereof. Then, associated liner interface guide elements110are attached to each of the fastening bolts130. As already explained, this will lock the fastening bolts130and the liner interface guide elements110to their respective liner element through-holes16as a result from the relative cross-sectional dimensions discussed earlier. Each liner interface guide element110protrude out from the back side12of the liner element10to define an associated guide portion112.

In a next step, the liner element10is lifted by means of a lifting tool60into a position with respect to the mill shell2at which the liner interface guide elements110axially coincide with associated mill shell through-holes2. This is the position illustrated inFIG.3A. The lifting tool60is typically maneuvered by a mill reline machine which is operated inside the mill. A lifting tool may be configured to lift the liner elements in different ways. One alternative is to use dedicated lifting points (not shown) available on the liner elements10. Such dedicated lifting points are well known in the art and will not be further described herein. Another, preferred, alternative is to lift the liner element10by the bolt heads132using a lifting tool structured and arranged to engage with the bolt heads132when the bolt heads132are protruding out from the front side14of the liner element10(FIG.3A). For such example embodiments of the method, the fastening bolts130and their associated liner interface guide elements110attached thereto are first arranged such that their bolt heads132protrudes out from the front side14of the liner element10, and the liner element10is then lifted by engaging the lifting tool with the protruding bolt heads132. Consequently, the bolt heads132for such example embodiments will act as lifting points. As readily appreciated by the person skilled in the art, it is not necessary to use all bolt heads132as lifting points. In the example embodiments, the outermost two bolt heads are used as lifting points, as indicated inFIG.3with the letter L enclosed by a circle. The lifting tool60, which is indicated in the drawings, is an example embodiment of a lifting tool which is arranged to lift the liner element using the bolt heads as lifting points. There are many alternative ways of lifting the liner element10by engaging the bolt heads132according to the inventive concept. Therefore, the lifting tool60is only schematically indicated herein.

In a next step, the liner element10is displaced, by means of the lifting tool60, into the mounting position at which the liner element10is in abutment with the mill shell2. This is achieved by allowing the guide portions112of the liner interface guide elements110to penetrate into the mill shell through-holes4as indicated inFIG.3Aby the dotted lines. This way, the liner element10will be guided into said mounting position more or less by itself, without any assistance either from manual supervision or from dedicated e.g. sensor-based control systems on the mill reline machine in order to identify where the mill shell through holes4are located in relation to the liner element10to be mounted. Once at the mounting position, each guide portion112will at least partly protrude out from the mill shell2on the outside thereof so as to present an externally accessible engagement portion118. This is illustrated inFIG.3B. The engagement portion118is large enough to allow engagement by hand or by a tool as will be described later.

In a next optional step, locking means150are activated for temporarily locking the liner element10to the mill shell2. The locking means150thus provides an engagement between the engagement portions118and the mill shell2prior to (permanently) securing the liner element10using said associated fasteners140. The locking means150allows to temporarily lock the liner element10with respect to the mill shell2may be advantageous as it may prevent the liner element10from accidentally falling down during mounting thereof. The locking means150may thus provide an extra security during the mounting process. However, as can be deduced from analysing the relative geometry of the liner interface guide elements110and their associated fastening bolts130in relation to the liner element10and the mill shell2inFIG.3B, the locking engagement achieved by the locking means150should not be construed as a fixed attachment which forces the liner element10to stay in the mounting position at all times. Clearly, the liner element10may in principal 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 means150. Therefore, it is preferred that the liner element10is held firmly in position against the mill shell2by the mill reline machine until the liner element10has been secured to the mill shell2by at least one fastening bolt130and fastener140.

As illustrated inFIG.3B. the locking means150may be defined by a locking through-hole152formed in each engagement portion118, and an associated locking element154arranged to be received in said locking through-hole152. This is illustrated for the example embodiment, andFIG.3Bclearly illustrates how the locking elements154are inserted into the locking holes152on the outermost two liner interface guide elements110.

In a next step, each liner interface guide element110and its associated fastening bolt130are displaced with respect to the liner element10to a fastening position at which the bolt head132engages with the liner element10. This step is illustrated inFIG.3Cfor the middle liner interface guide element110. Once in the fastening position, the liner interface guide elements110are removed from their associated fastening bolts130. For the example embodiment, this is achieved by rotating the liner interface guide element110with respect to the liner element10e.g. using a wrench tool or spanner for engaging the tool-connecting portion119so as to unscrew the liner interface guide element110from its associated fastening bolt130. The asymmetric cross section of the bolt head152which is structured and arranged to fit into the complementary shaped liner element through-hole16effectively prevents the fastening bolt130from rotating with the liner interface guide element110.

Once the liner interface guide element110has been removed from the fastening bolt130, its fastener attachment portion138will be revealed, as illustrated inFIG.3D. The next step will be to secure the fastening bolt130from outside the mill shell2using an associated fastener140. This is illustrated inFIGS.3Eand F. Preferably, a collar160is first disposed around the bolt body134of the fastening bolt130inside the mill shell through-hole2. This may prevent unnecessary bolt movement which may occur as the cross-sectional dimension D4of the mill shell through-hole4is larger than the optimum dimension for the bolt body134.

As readily appreciated by the person skilled in the art it is not essential that the number of liner interface guide elements110and fastening bolts130are equal. To fasten a liner element to a mill shell, two, four or even more fastening bolts130may 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 element110. However, two liner interface guide elements110are 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 element10is lifted by means of the bolt heads132of the fastening bolts130, it is essential that those fastening bolts130that serves as lifting points are all attached to associated liner interface guide elements110, or to any other element having a larger cross-sectional dimension than the minimum cross-sectional dimension D3of the waist portion18of the liner element through-hole16, so as to prevent the fastening bolt130from escaping said liner element through-hole16. It is however preferred to attach liner interface guide elements110to all fastening bolts130, as it reduces the risk that a fastening bolt130accidentally falls out from its liner element through-hole16during 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 fasteners140, here illustrated as fastening nuts140) are removed from their associated fastening bolts130. Typically, at least one fastener140is 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 element10by the bolt heads132, as there may for those embodiments be no other way to engage the lifting tool60of the mill reline machine with the liner element10prior to unfastening at least one of the fasteners140. Engaging the lifting tool60with the liner element prior to finishing the unmounting process is preferred as it reduces the risk that the liner element10falls down into the mill prior to being properly engaged by the lifting tool60. One or more liner interface guide elements110are then attached to the unsecured fastening bolts. Optionally, locking means150are activated to temporarily lock the liner element10to the mill shell2. At least one fastening bolt130having an attached liner interface guide element110is then displaced, typically by using a bolt hammer, such that the bolt head132protrudes out from the front side14of the liner element10to define lifting points for the lifting tool60. The mill reline machine can then be operated to manoeuvre the lifting tool60to engage with lifting points of the at least one fastening bolt130. Alternatively, the mill reline machine can instead be operated to manoeuvre the lifting tool60to engage with alternative lifting points on the liner element, e.g. of conventional type. Once the liner element10is held firmly in position against the mill shell2by the mill reline machine, the remaining fasteners140may be removed. Optionally, associated liner interface guide elements110may be attached to the last fastening bolts130. Finally, when all fasteners140have been removed, the mill reline machine may manoeuvre the lifting tool60to remove the liner element from the mill shell2.

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.