Patent Application
20240226909
The present disclosure relates to a system and methods for mounting and demounting 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 and/or demounting 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 an important step in achieving unassisted relining. The system of the disclosure provides this interface by the one or more liner lifting elements which each present a respective lifting portion. Once the liner element has been mounted in its intended position, the one or more liner lifting elements can be removed and re-used for other liner elements. A 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.
The term “fastening bolt” should herein be construed as encompassing not only fastening bolts where the bolt head is integrally formed with the bolt body, but also combinations of two or more elements which together form the exact same function, such as e.g. a threaded pin engaging a nut.
Each of the one or more fastening bolts may be structured and arranged to fasten the liner element to the mill shell via a liner element through-hole and an associated mill shell through hole, respectively.
Each fastening bolt may be inserted from the inside of the mill. Each fastening bolt may then for example be fastened using a fastener, such as a fastening nut disposed at the outside of the mill shell.
Alternatively, each of said one or more fastening bolts may be inserted from outside the mill shell.
According to some embodiments, each of said one or more fastening bolts is structured and arranged to be inserted into an associated mill shell through-hole from outside the mill shell and to be threadedly engaged with the liner element. This may be advantageous as it allows the fastening to be made from outside the mill. Moreover, by threadedly engaging the fastening bolt with the liner element, no additional fastening element, such as e.g. a fastening nut, is needed which further simplified the fastening.
According to some embodiments, the lifting portion of each liner lifting element presents protrusions and/or recesses at an engagement surface thereof. Providing such protrusions and/or recesses may provide a better grip for the lifting tool. The protrusions and/or recesses may be embodied for example by providing a threaded or a ribbed engagement surface.
According to some embodiments, each liner lifting element comprises a tool engagement portion for engagement with a fastening tool. The tool engagement portion may be embodied in many ways. The tool engagement portion may for example be in the form of an opening having a non-circular rotational cross section disposed at an end of the liner lifting element, such as e.g. a female hexagonal portion adapted to be engaged with a hexagonal key. Alternatively, the tool engagement portion may be a portion of the liner lifting element having a non-circular rotational cross section. Such a cross section could for example be a hexagonal cross section adapted to be engaged by e.g. a wrench. A tool engagement portion may be advantageous as it allows engaging with a fastening tool during mounting and dismounting of the liner lifting elements.
According to some embodiments, each liner lifting element are further structured and arranged to be fastened in said respective liner element through-hole such that said one or more liner lifting elements protrude out from the back side of the liner element to define associated guide portions which, during a mounting of the liner element on the mill shell, are arranged to penetrate into associated mill shell through-holes thereby guiding the liner element into a mounting position at which the liner element is in abutment with the mill shell. This may be advantageous as the guide portions may facilitate 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. This makes it possible to mount liner elements also in absence of a supporting function, such as e.g. manual guidance by staff and/or an assistant system, such as a dedicated sensor system on the mill reline machine.
According to some embodiments, the guide portion of each liner lifting 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 of the one or more fastening bolts is structured and arranged to partly, or completely, fill the respective liner element through-hole when the fastening bolt is fastened. This implies that the liner element through-holes may be plugged by means of the fastening bolts on the front side of the liner element. This may be advantageous as it may protect the liner element through-hole from damage during mill operation. Preferably, the fastening bolts are structured and arranged to completely fill the respective liner element through-holes when the fastening bolts are fastened. This may decrease the risk of damage to the openings of the liner element through-holes which faces the interior of the mill.
According to some embodiments, each of the one or more fastening bolts comprises a sacrificial end portion arranged to face an interior of the mill when the fastening bolt is fastened. This implies that the sacrificial end portion at least partly fills the respective liner element through-hole when “the fastening bolt is fastened. The sacrificial end portion may be advantageous as it allows further protecting the liner element through-hole from damage during grinding mill operation. As the liner element wears, the sacrificial end portion will wear down with it while maintaining its protective effect on the liner element interface through-hole.
According to some embodiments, the sacrificial end portion comprises a wear resistant material such as rubber, polyurethane, or steel. The wear resistant material may advantageously be the same as a wear resistant material of the liner element. This means that a sacrificing portion comprising rubber may be more appropriate for a liner element having a rubber wear portion, whereas a sacrificing portion comprising steel may be more appropriate for a liner element having a steel wear portion. However, it is conceivable that the wear resistant material of the sacrificial end portion is a different material than the material of the liner wear portion.
According to some embodiments, the sacrificial end portion comprises an outer portion arranged to face the interior of the mill and an inner resilient portion. This implies that the inner resilient portion interconnects the outer portion with the rest of the fastening bolt. This may be advantageous as it allows reducing the influence of impact on the fastening bolts having a sacrificial portion comprising a hard material such as steel. For such fastening bolts, there would otherwise be no means of damping impact forces which occur due to material hitting the sacrificial end portion on the inside of the mill during use. Such impact forces are unwanted as they increase the mechanical stress on the bolts and/or the liner element though-openings and may lead to mechanical damage thereof.
According to some embodiments, each of said one or more liner lifting elements has a threaded fastening portion for fastening the liner lifting element to an associated liner element through-hole by threaded engagement. The threaded engagement is a preferred fastening means as it is reliable. However, other fastening means are conceivable, such as e.g. a snap fit fastening system.
According to some embodiments, each liner lifting element and each fastening bolt are structured and arranged to threadedly engage with an inner threaded portion of the associated liner element through-hole. This embodiment implies that the threaded fastening portion of the liner lifting element has the same properties as a threaded fastening portion of the fastening bolts. This may be advantageous as it allows a simplified system as both the liner lifting elements and the fastening bolts share one and the same fastening portion.
According to a second aspect there is provided a liner assembly for a mill comprising:
According to some embodiments, the liner element comprises a backing plate arranged at the back side of the liner element. The backing plate may be equipped with tapped through-holes providing said threaded portion. The liner element may further comprise a main wear portion arranged on the backing plate. The liner element may however further comprise a steel reinforcement portion arranged on the main wear portion. This steel reinforcement portion may be preferred for liner elements having a main wear portion comprising a resilient material, such as rubber or polyurethane.
For some liner elements, such as e.g. liner elements having a main wear portion made of steel or other hard metal or metal alloy, the liner element may comprise the backing plate and the main wear portion only. Alternatively, the liner element may be provided without a backing plate. Such liner elements may be integrally formed from one piece of material, such as e.g. steel or a steel alloy. This implies that the inner threaded portions of the liner element through-holes may also be integrally formed in the liner element.
A cross sectional area of said one or more liner element through-holes may be larger in through-hole portions connecting to the front side of the liner element than in through-hole portions connecting to the back side of the liner element. This may be advantageous as providing a somewhat oversized hole at the front side of the liner element may prevents peening from excessively reducing the hole size during use.
For liner elements having a main wear portion and a steel reinforcement portion, the cross sectional area of said one or more liner element through-holes may be larger in through-hole portions extending through the steel reinforcement portion than in through-hole portions extending through the main wear portion.
According to a third aspect there is provided a method for demounting a liner element from 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, said one or more fastening bolts are unfastened, and removed, from said one or more associated liner element through-holes of the liner element from outside the mill shell. In other words, the one or more fastening bolts may be removed from outside the mill shell.
The one or more liner lifting elements may be inserted from outside the mill shell. This implies inserting the one or more liner lifting elements into said one or more associated liner element through-holes via associates mill shell through-holes. The one or more liner lifting elements may be fastened from outside the mill shell. This implies that the one or more liner lifting elements may be engageable by a fastening tool from outside the mill shell. Alternatively, the one or more liner lifting elements may be inserted from inside the mill shell. The one or more liner lifting elements may be fastened from inside the mill shell.
According to a fourth aspect there is provided a method for mounting a 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, said one or more liner lifting elements are removed from outside the mill shell, and the liner element is fastened to the mill shell from outside the mill shell by inserting said at least one fastening bolt into associated mill shell through-holes from outside the mill shell, and threadedly engaging said at least one fastening bolt with the liner element.
As readily appreciated by the person skilled in the art, for liner elements having two or more liner element through-holes, and where two one or more liner lifting elements are used, the step of fastening the liner element to the mill shell by at least one fastening bolt and the step of removing said one or more liner lifting elements may be undertaken interchangeably. Once the liner element has been displaced into the mounting position, a first liner lifting element may be removed to reveal the threaded engagement portion of the associated liner element through-hole. A fastening bolt may then be introduced to fasten the liner element to the mill shell at that hole. This process may then be continued.
As readily appreciated by the person skilled in the art, the method for mounting a liner element disclosed herein may equally well be performed in reverse thereby defining a method for removing a liner element from a mill shell of a mill.
Effects and features of the second, third and fourth 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, third and fourth 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
The inventive concept presented here aims to solve both these problems at the same time by providing liner elements having through-going holes, here termed “liner element through-holes” and dedicated elements, here termed “liner lifting elements” which elements have both a guiding function to facilitate guiding the mill reline machine to manoeuvre the liner element to the correct position, and an engaging function providing dedicated lifting points for the mill reline machine. The inventive concept should however not be construed as limited to the combination of these two functions. Rather, as mill reline machines at some facilities may be perfectly capable of guiding a liner element to a correct position without the need for the disclosed guiding functionality, e.g. by means of a supporting function, such as e.g. manual guidance by staff and/or an assistant system, such as a dedicated sensor system on the mill reline machine, the liner lifting elements of the disclosure may alternatively be embodied without dedicated guiding portions.
Example embodiments of the liner elements 10 and 10″ of the inventive concept will first be described with reference to
The invention should not be construed as limited to wear liners of the kind illustrated in
A liner lifting element will now be described with reference to
As can be seen in
Although not illustrated here, liner lifting element 110 will engage in a similar way with a liner element, such as the liner element 10. As readily appreciated by the person skilled in the art, the only difference will be that, as the liner lifting element 110 lacks a guide portion, it will not protrude on the outside of the mill shell 2. The reader is referred to
The fastening bolts 130,230 are structured and arranged to partly, or completely, fill the respective liner element through-hole 16 when the fastening bolt 130,230 is fastened. Preferably, the fastening bolts 130,230 are completely filling the liner element through-holes 16. However, it is conceivable that they only partly fill the liner element through-holes 16. In the latter case, a recently installed liner element may present openings on the front side 14 having a certain depth. After a certain degree of wear during use, the liner element 10,10″ will wear down which effectively will move the front side 14 with respect to the fastening bolts 130 until the sacrificing end portions 132,232 becomes flush with the front side 14 of the liner element 10,10″. At that time and onwards, the sacrificing end portions 132,232 will wear down together with the liner element 10, 10″ as will be described above.
Although the inventive concept is presented here with fastening bolts 130;230 which are inserted and fastened from outside the mill shell, the inventive concept should not be construed as limited to such fastening bolts only. As an alternative, each fastening bolt may instead be inserted from the inside of the mill. Each fastening bolt may then be fastened by a fastener, such as e.g. a fastening nut, disposed at the outside of the mill shell. As readily appreciated by the person skilled in the art, the fastening bolts for such embodiments of the invention will be structurally different from the fastening bolts 130;230 described herein. For example, one kind of fastening bolts well known in the art presents bolt heads having a nonuniform rotational cross sections configured to fit in a geometrically complementary liner element through hole of the liner element for preventing the fastening bolts to rotate with respect to the liner element during fastening thereof. As such fastening bolts are well known in the art, they are not further described here.
Different parts of the inventive concept have now been described in detail with reference to
A method for mounting a liner element to a mill shell of a mill will now be described with reference to
The method for mounting a liner element to a mill shell of a mill comprises fastening one or more liner lifting elements 210 in one or more associated liner element through-holes 16 such that said one or more liner lifting elements 210 protrude out from the back side 12 of the liner element 10 to define associated guide portions 212 and protrude out from the front side 14 of the liner element 10 to define associated lifting portions 114. The liner lifting elements 210 may be fastened in advance, or just prior to mounting the liner element 10. As illustrated in
The method further comprises engaging a lifting tool 60 with at least one of said associated lifting portions 114. The lifting tool 60 is operated by the mill reline machine. There are many alternative ways of lifting the liner element 10 by engaging the lifting portions 114 of the liner lifting elements 110 according to the inventive concept. Therefore, the lifting tool 60 is only schematically indicated herein.
The method further comprises lifting by means of the lifting tool 60 the liner element 10 into a position with respect to the mill shell 2 at which the one or more liner lifting elements 210 axially coincide with one or more associated mill shell through-holes 4. This is illustrated in
The method further comprises fastening the liner element 10 to the mill shell 2 by at least one fastening bolt 130. This is illustrated in
The method further comprises removing the one or more liner lifting elements 210 from the liner element 10. This is illustrated in
As readily appreciated by the person skilled in the art it is not essential that the number of liner lifting elements 110 and fastening bolts 130 are equal. To fasten a liner element to a mill shell, two, four or even more fastening bolts may be needed dependent on the liner element dimensions, the dimensions of the fastening bolts, and the physical requirements for the mill. However, for lifting, and guiding, a liner element to a mounting position on the mill shell, it may suffice with only one liner lifting element. However, preferably two liner lifting elements 210 are used to provide better stability during the lift procedure, as well as more accurate guiding towards of the liner element towards the mounting position.
As readily appreciated by the person skilled in the art, the method may also be performed using liner lifting elements 110 according to the first example embodiment. The difference to the described method is merely that the method steps related to the guiding are not undertaken. The mill reline machine must in this case be able to accurately place the liner element at a correct position without any guidance from the liner lifting elements.
As readily appreciated by the person skilled in the art, the same general procedure may be used when demounting a worn-out liner element from the mill, although in reverse. This is illustrated in
First, one or more fastening bolts 130 are unfastened, and removed, from the liner element 10 as illustrated in
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 |
|---|---|---|---|
| 21181260.7 | Jun 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/065699 | 6/9/2022 | WO |
