Field of the Invention

[001] The present invention relates to wear detection apparatus, in particular for detecting wear on wear-bearing surfaces of mining equipment. [002] The invention has been developed primarily for use in grinding rolls and related technologies, e.g. high-pressure grinding roll (HPGR) apparatus, and will be described hereinafter with reference to these applications. However, it will be appreciated that the invention is not limited to this particular field of use. Background of the Invention [003] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

[004] A typical HPGR apparatus includes a pair of grinding rolls, where each of the grinding rolls is provided with harder wear members on an external surface. The wear members may be aligned in a plurality of rows, with each row extending for substantially the entire length of the tyre, and the rows are arranged circumferentially around the tyre. The arrangement of the wear members improve the grinding efficiency between the grinding rolls and improve the service life of the HPGR apparatus by providing a hardened wear surface. However, due to the high compressive forces present during operation of the HPGR apparatus, the wear members experience significant wear and can be dislodged or damaged during operation. Any loss or damage of wear members greatly reduces the efficiency of the HPGR apparatus.

[005] Historically, it has been difficult to detect any damage to, or loss of, wear members during operation of the HPGR apparatus, as this process required stopping the rotation of the grinding rolls in the HPGR and performing a manual inspection thereof, which is highly disadvantageous from a production throughput standpoint. Accordingly, these wear members are often only checked during scheduled apparatus shutdown periods, which may occur days or weeks after significant damage had occurred to the wear members or the grinding roll surface. [006] Recent developments to the monitoring grinding roll wear have been disclosed in, for example, patent documents W02008/090016 and DE202015106156, in which a monitoring device is provided to scan the surface of the grinding rolls to detect wear during operation. However, the systems described in such documents are deficient in that they are not able to account for surface variations which may be caused by, for example, the formation of an autogenous wear layer formed during operation of the grinding roll, or from vibrations or grinding roll skew in use. Accordingly, these systems would not be able provide an accurate determination of wear during normal use of the grinding roll.

[007] A further development to address this issue is disclosed in WO201 4/068453, where the monitoring device further includes a light emitter/laser that projects a line on the surface of the grinding roll. This line is also recorded by the monitoring device and is used to analyse the image; however, as this line is provided from substantially the same location as the monitoring device, this system would be similarly deficient for detecting an overall topography of the grinding roll, or any surface variations caused by formation of an autogenous wear layer formed during operation of the grinding roll, or from vibrations or grinding roll skew in use.

[008] Moreover, it is noted that these prior systems do not account for the large amount of dust and particulates produced during HPGR operation, which may obscure or block the monitoring device during normal operation.

Summary of the Invention

[009] It is an object of one or more embodiments of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[010] According to a first aspect of the invention, there is provided a wear detection apparatus for detecting wear of a grinding roll, comprising: a housing; a scanning sensor supported within the housing; a controller coupled to the scanning sensor and operable to control the scanning sensor to scan a surface section of the grinding roll to determine wear, or absence, of wear members on the grinding roll; and at least one alignment sensor mounted within the housing operable to sense a reference mark on the grinding roll for determining a relative location or alignment position of the scanning sensor to the grinding roll, wherein the reference mark is an indentation or projection on a surface of the grinding roll. [011] In some embodiments, the reference mark may comprise an indentation. In other embodiments, the reference mark may comprise a projection. In still other embodiments, the reference mark may comprise an indentation for part of a circumference of the grinding roll, and then a projection for another part of the circumference. The indentation or projection is preferably distinct to facilitate easy location and identification thereof.

[012] In certain embodiments, the wear detection apparatus may be adapted for detecting wear on an exterior surface of the grinding roll. Optionally, this exterior surface may be a tyre surrounding the grinding roll. [013] In certain embodiments, the wear members may be any member exposed on the exterior surface of the grinding roll that may be worn during operation of the grinding roll. In some embodiments, the wear members may be manufactured of a material harder than the bulk material of the grinding roll. In some embodiments, the wear members may be integrally formed with the grinding roll, or otherwise mounted on the grinding roll; for example, the wear members may comprise grinding studs positioned in and protruding from apertures on the grinding roll, or the wear members may be welded on the surface of the grinding roll, or edge protectors coupled to an edge of the grinding roll.

[014] In an embodiment, the apparatus comprises only one scanning sensor. [015] In further embodiments, the apparatus comprises two or more scanning sensors.

[016] In an embodiment, the apparatus further comprises a rail mounted within the housing parallel to a longitudinal axis thereof, and on which a carriage is slidably mounted, the scanning sensor being coupled to the carriage for movement therewith.

[017] In certain embodiments, at least one alignment sensor is independent from the carriage.

[018] In further embodiments, the at least one alignment sensor is positioned to be stationary in use. [019] In certain embodiments, at least one alignment sensor is coupled to the carriage for movement therewith. Alternatively, the at least one alignment sensor is may be coupled to a separate rail for independently movement to the carriage. [020] In an embodiment, the housing defines a scanning window and the controller is operable to slide the scanning sensor to a scanning position on the rail at which the scanning sensor scans at least part of the surface section of the grinding roll. Optionally, the scanning sensor may conduct this scan during rotation of the grinding roll.

[021] In an embodiment, the wear detection apparatus comprises a plurality of scanning windows spaced along a longitudinal surface of the housing, and the controller is operable to slide the scanning sensor to each of a plurality of scanning positions on the rail, each position corresponding to, and being aligned with, one of the scanning windows, and the scanning positions being selected such that substantially all of a length of the grinding roll is scanned as the surface section of the grinding roll.

[022] In further embodiments, the wear detection apparatus comprises a plurality of scanning sensors at a plurality of scanning positions being aligned with a plurality of scanning windows spaced along a longitudinal surface of the housing, such that substantially all of a length of the grinding roll is scanned as the surface section of the grinding roll.

[023] In further embodiments, the wear detection apparatus comprises one alignment sensor mounted along the longitudinal axis at one end of the housing. [024] In further embodiments, the wear detection apparatus comprises two alignment sensors mounted along the longitudinal axis at each end of the housing. [025] In certain embodiments, the scanning sensor and each of the at least one alignment sensor are distinct (or separate) sensors.

[026] In certain embodiments, the scanning sensor and at least one alignment sensor are physically separated. In further embodiments, the scanning sensor and each of the alignment sensors are physically separated.

[027] In certain embodiments, the at least one alignment sensor is an image scanning sensor or a laser scanning sensor.

[028] In further embodiments, the reference mark may be a visual indicator. In certain embodiments, the reference mark may be continuous, such as a complete or dashed circumferential line/indentation/projection, or non-continuous, such as a singular point or an incomplete circumferential line/indentation/projection. [029] In certain embodiments, the reference mark may be a reference ring mounted to the grinding roll. In further embodiments, the reference ring comprises the indentation or projection, which may be continuous or non-continuous.

[030] In further embodiments, the reference ring has a diameter less than the diameter of the grinding roll. Alternatively, in some embodiments, the reference ring has a diameter equal to the diameter of the grinding roll.

[031 ] In certain embodiments, the reference mark may be on an axial face of the grinding roll. Alternatively, the reference mark may be on a radial face of the grinding roll, or present on both the axial and radial faces. [032] In further embodiments, the at least one alignment sensor is operable to sense two or more reference marks on the grinding roll.

[033] In an embodiment, the controller is operable to use measurements from the at least one alignment sensor for correcting alignment deviations of the scanning sensor during rotation thereof. In certain embodiments, the alignment deviations may be caused by roller skewing and/or vibrations.

[034] In certain embodiments, the alignment sensor(s) are adapted to sense a plurality of reference marks on the grinding roll for correcting alignment deviations. [035] In certain embodiments, the wear detection apparatus comprises two or more alignment sensors distantly mounted in the housing, each alignment sensor adapted to sense separate reference marks on the grinding roll.

[036] In some embodiments, the controller uses real-time measurements from the at least one alignment sensor for correcting alignment deviations. In further embodiments, the controller uses a plurality of measurements for correcting alignment deviations, for example by using an average of the plurality of measurements.

[037] In an embodiment, the housing defines an internal area substantially sealed from a crushing area of the grinding roll and pressurised above ambient pressure. [038] In further embodiments, the housing is pressurised by a blower, such as an air blower. In certain embodiments, the blower may be internal or external to the housing.

[039] In an embodiment, the apparatus further comprises a processor, and the controller includes a transceiver operable to transmit a scan of the surface section of the grinding roll to the processor to determine wear or absence of the wear members.

[040] In an embodiment, the processor is programmed to process a plurality of scans to create a single scan extending for the length of the grinding roll from a plurality of scans received from the controller, and to identify any areas of wear or an absence of wear members across that length.

[041] In an embodiment, the processor is programmed to create, from a plurality of single length scans, a composite scan of the entire circumference of the grinding roll thereby constructing a topology of the entire grinding roll surface. [042] In further embodiments, the composite scan or the topology is interpreted to determine an overall surface wear status of the grinding roll. In certain embodiments, the overall surface wear status is interpreted to determine whether maintenance is required on the wear members on the grinding roll.

[043] In further embodiments, the controller is configured to scan the surface section of the grinding roll continuously.

[044] In further embodiments, the controller is configured to scan the surface section of the grinding roll at predetermined intervals.

[045] In further embodiments, the controller is configured to scan the grinding roll for one revolution to scan a circumferential surface section. [046] In further embodiments, the controller is configured to scan the grinding roll for two or more revolutions and the processor is configured to determine an average circumferential surface section based on the scan.

[047] In an embodiment, the processor is located externally of the housing.

[048] In further embodiments, the processor is located internally of the housing. [049] In an embodiment, the scanning sensor is a 3D image scanning sensor or a laser scanning sensor.

[050] In an embodiment, the wear detection apparatus determines wear or absence of wear members on the grinding roll by measuring a distance from the scanning sensor to the surface section of the grinding roll and identifying where such distance is below a threshold value.

[051] In further embodiments, the threshold value is determined from a mounting distance of the wear detection apparatus to the grinding roll. [052] In further embodiments, the threshold value is determined from a distance from the alignment sensor to the reference mark.

[053] According to a second aspect of the invention, there is provided a method of detecting wear of a grinding roll, the method comprising: moving a scanning sensor on a rail within a housing in a direction generally parallel to a longitudinal axis of the grinding roll being measured; capturing height information relating to a surface of the grinding roll on which a plurality of wear members were originally disposed; sensing a reference mark on the grinding roll with an alignment sensor on the housing for determining an alignment position of the scanning sensor, wherein the reference mark is an indentation or projection on a surface of the grinding roll; and ascertaining wear, or absence, of the wear members by comparing the captured distance of the grinding roll surface at locations at which the wear members are expected with distance information corresponding to unworn wear members. [054] In an embodiment, the method further comprises: transmitting to a processor an output indicating the amount of wear detected by the wear detection apparatus.

[055] In an embodiment, the step of moving the scanning sensor on the rail is performed periodically at predetermined intervals. [056] In an embodiment, the step of moving the scanning sensor on the rail is performed continuously as the grinding roll is rotated.

[057] In an embodiment, the method is conducted with the wear detection apparatus of the first aspect.

[058] In an embodiment, the step of sensing a reference mark on the grinding roll with an alignment sensor on the housing includes ascertaining a distance of the reference mark from the alignment sensor and comparing the ascertained distance with a distance corresponding to an unskewed orientation of the grinding roll to calculate a skew angle of the grinding roll. In addition to ascertaining the skew angle, the method may include ascertaining an offset (distance) of the reference mark from an expected (unskewed) position of the reference mark. The skew angle and offset may be used to calibrate the captured distances of locations at which the wear members are expected, thereby providing a calibrated height of the wear members that takes account of the skew. The calibrated height may then be compared with distance information corresponding to unworn wear members. [059] According to a third aspect of the invention, there is provided a grinding roll apparatus comprising: a first grinding roll having wear members mounted circumferentially thereon; a second grinding roll having wear members mounted circumferentially thereon; a wear detection apparatus according to the first aspect mounted in proximity to one of the grinding rolls and operable to detect wear or absence of wear members on the surface of that grinding roll, wherein at least one of the first grinding roll and the second grinding roll includes a reference mark for determining a relative location or alignment position of the scanning sensor of the wear detection apparatus to the grinding roll.

[060] In certain embodiments, the reference mark may include a visual indicator. In certain embodiments, the reference mark may be continuous, such as a complete or dashed circumferential line / indentation / projection, or non- continuous, such as a singular point or an incomplete circumferential line / indentation / projection.

[061] In an embodiment, the first grinding roll is coupled to an actuator operable to move the first grinding roll towards the second grinding roll during operation of the grinding roll apparatus. [062] In further embodiments, the wear detection apparatus is operable to detect wear or absence of wear members on the surface of the first grinding roll and adjusts for actuator distance variations by scanning of the reference mark.

[063] In further embodiments, the wear detection apparatus is operable to detect wear or absence of wear members on the surface of the first grinding roll and is coupled to the actuator to move concurrently with the first grinding roll.

[064] In an embodiment, the grinding roll apparatus further comprises a grinding roll apparatus controller operable to counter-rotate the grinding rolls and to provide the wear detection apparatus with a signal indicating a speed of rotation of the grinding rolls. [065] In an embodiment, the reference mark includes a visual indicator on the grinding roll.

[066] In an embodiment, the reference mark is a projection at a longitudinal end of the first grinding roll or a second grinding roll. In certain embodiments, the projection is a cylindrical projection having a diameter less than the first grinding roll or the second grinding roll, such that the reference mark is recessed to the grinding roll surface.

[067] In an embodiment, the reference mark is continuous about the grinding roll circumference. In an alternative embodiment, the reference mark is non- continuous about the grinding roll circumference.

[068] In an embodiment, the grinding roll apparatus comprises a plurality of reference marks. In certain embodiment, the plurality of reference marks are spaced at predetermined positions along a longitudinal axis of the first grinding roll or the second grinding roll. In further embodiments, the predetermined positions are symmetrical along the longitudinal axis. In further alternative embodiments, the predetermined positions are not symmetrical along the longitudinal axis.

[069] It should now be appreciated that certain embodiments provide a reference mark that has three functions: to indicate a starting (and end) point from which measurements of wear members should be taken; to enable a skew angle of the roller to be ascertained; and to enable heights of wear members to be normalised with respect to the skewing (for example, using a measured offset and the skew angle).

[070] Other aspects, features, and advantages will become apparent from the following Detailed Description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of the various embodiments.

Brief Description of Drawings

[071] Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[072] Figure 1 is a simplified schematic diagram illustrating a grinding roll assembly including a wear detection apparatus according to an embodiment of the invention;

[073] Figure 2 is a partial cut-away schematic view of part of the wear detection apparatus of Figure 1, the left side illustrating an external view and the right side illustrating an internal view; [074] Figure 3 is a simplified schematic view illustrating part of the wear detection apparatus (a sensor mounted on a carriage) of Figure 2 in relation to part of the grinding roll assembly (a grinding roll tyre) of Figure 1 ; and [075] Figure 4 is a simplified schematic of an alternative grinding roll tyre to that shown in Figure 3.

Detailed Description

[076] The following embodiments are described by way of example only to provide a more detailed understanding of certain aspects of the invention. It is to be understood that other embodiments are contemplated, and it is not intended that the disclosed invention is limited to the following description.

[077] Referring initially to Figure 1 , there is illustrated an example high-pressure grinding roll apparatus 10 suitable for use with the disclosed invention, including a movable grinding roll 11, a fixed grinding roll 12, and a hydraulic actuator 13 coupled to the movable grinding roll 11 operable to move the movable grinding roll 11 toward or away from the fixed grinding roll 12 during operation of the apparatus

10.

[078] The movable grinding roll 11 and the fixed grinding roll 12 are counter- rotatable using appropriate means (not depicted) to define a crushing area 14 between them, and both the movable grinding roll 11 and the fixed grinding roll 12 are fitted with a respective tyre 15, 16 mounted circumferentially around its respective grinding roll 11, 12. Each grinding roll tyre 15, 16 includes a plurality of wear-resistant grinding studs 18 (shown enlarged in Figure 1 for clarity) protruding from corresponding apertures therein. The studs 18 are removable and replaceable in the event that they are worn down and/or dislodged from the grinding roll tyres 15, 16.

[079] In operation of the apparatus 10, a material to be crushed (e.g. rocks or ores) is fed to the crushing area 14 while the movable grinding roll 11 and the fixed grinding roll 12 are counter-rotated and the hydraulic actuator 13 drives the movable grinding roll 11 toward the fixed grinding roll 12. As is known, the combination of the grinding rolls counter-rotating and the hydraulic actuation provides high-pressure compression forces in the crushing area 14 to crush the ore to a smaller size. During this operation, the wear-resistant grinding studs 18 are subjected to wear forces which may deteriorate their outer surfaces or dislodge them from the grinding roll tyres 15, 16, resulting in reduced crushing efficiency or damage to the surface of the grinding rolls.

[080] The wear status of each of the tyres 15, 16 (particularly the wear or absence of the grinding studs 18) is usually visually inspected during scheduled shutdown maintenance periods, and accordingly the apparatus 10 may operate at a reduced efficiency when significant wear to the grinding studs 18 is sustained between maintenance periods.

[081] This embodiment of the present invention provides wear detection apparatus 20 for detecting and determining wear, or absence, of the grinding studs 18 on the surfaces of the tyres 15, 16. In this embodiment, a pair of identical (or mirror imaged) wear detection apparatus units 20 are provided: one wear detection apparatus 20a is located above the moveable grinding roll tyre 15, and one wear detection apparatus 20b is located above the fixed grinding roll tyre 16. In other embodiments, the wear detection apparatus 20a, b may be positioned in a different location. As illustrated, the wear detection apparatus 20a, b are positioned away from the crushing area 14 to provide a clear line of sight to the surfaces of the tyres 15, 16.

[082] The components and operations of the wear detection apparatus 20 are further illustrated in Figure 2 and Figure 3. The wear detection apparatus 20 comprises a laser scanning sensor 21 and controller 22 mounted within a housing 23. The housing 23 is sealed from the crushing area 14, and internally pressurised above ambient pressure to prevent any dust or particulate matter entering the housing 23 or obstructing the scanning sensor 21. The housing 23 may be pressurised by an external or internal blower (not depicted) urging industrial grade air (or an inert gas) into the housing 23.

[083] The scanning sensor 21 and controller 22 are positioned on a carriage 25 mounted on a rail 26 which extends across a longitudinal axis (illustrated by broken line 27) of the housing 23. The controller 22 controls the operation of the scanning sensor 21 and also the position of the carriage 25 along the rail 26. This configuration provides for the controller 22 to move the scanning sensor 21 along the rail 26 to each of a plurality of scanning positions, in turn, where the scanning positions correspond to a plurality of scanning windows 28 defined by the housing 23. The distance of the scanning sensor 21 from the scanning windows 28, and the number and separation of the scanning windows 28 are all selected to ensure that the scanning sensor 21 is operable to scan substantially all of the length of the respective grinding roll tyre 15 or 16 with which the wear detection apparatus 20a or 20b is aligned. The controller 22 may be configured to scan the grinding roll tyre 15 or 16 at predetermined intervals or continuously.

[084] Reference is now made to Figure 3, which is a simplified schematic view illustrating the sensor carriage 25 aligned with grinding roll tyre 15. Figure 3 illustrates three distinct scanning positions (illustrated by boxes 31, 32, and 33), corresponding to three scanning windows 28, at each of which the sensor carriage 25 is stopped and the sensor 21 records scans of the surface of the tyre 15 at that location (scanning surface sections 31a, 32a, 33a, respectively). The sensor carriage 25 is stopped at each scanning window for long enough for the sensor 21 to record at least one full rotation of the tyre 15, but preferably a plurality of rotations in case dust or other particulate obscures some of the studs 18 during one rotation.

[085] The controller 22 is programmed to determine the wear or absence of the grinding studs 18 on the grinding roll tyre 15 by scanning a distance between the scanning sensor 21 and the surface sections (for example, 31a) of the grinding roll tyre 15. The wear or absence of the grinding studs 18 is determined by a scanned distance being less than a predetermined threshold distance value. Alternatively, the controller 22 may include a transceiver (not depicted) to transmit the scan to an external processor 40 (Figure 2) for determining the wear or absence of the grinding studs 18.

[086] The three scans are then combined by the controller 22 (or the external controller 40, if desired) to form a single scan extending the length and circumference of the grinding roll tyre 15 to identify any areas of wear or an absence of a grinding stud 18 on the tyre 15. This effectively maps the circumference of the tyre 15 onto a two-dimensional image for viewing by an operator. This two-dimensional map also allows the operator to locate any apertures corresponding to missing studs 18.

[087] The wear detection apparatus 20 further comprises at least one alignment sensor 29 (Figure 2) which may either be positioned in stationary position(s) within the housing 23 or may be movable cooperatively with, or independently of, the carriage 25. In the illustrated example, the wear detection apparatus 20 comprises one alignment sensor 29 secured at one end of the housing 23.

[088] The alignment sensor 29 is used to determine a relative location or an alignment position for the scanning sensor 21 relative to the grinding roll tyre 15 or 16, such that the controller 22 and/or the processor 40 may correct for alignment deviations of the scanning sensor 21 during rotation of the grinding roll tyre 15 or 16, for example from skewing or vibrations of the grinding rolls 11 or 12, respectively. In this embodiment, this is performed by the alignment sensor 29 sensing a reference mark 19 on the grinding roll tyre 15. The reference mark 19 has been depicted as a continuous dashed circumferential groove in the grinding roll tyre 15 with a longitudinal notch (to assist with indicating a complete revolution, or an absolute circumferential position relative to this notch). However the reference mark 19 may be any detectable indicator on the roll tyre 15 or 16. For example, the reference mark may be a visual indicator, or an indentation or projection on the surface of the roll tyre, and continuous (e.g. a complete or dashed circumferential line / indentation / projection) or non-continuous (e.g. a singular visual point / indentation / projection or an incomplete circumferential line / indentation / projection) around the circumference of the of the grinding roll tyre 15 or 16. In some applications, it may be beneficial to have a plurality of reference marks at predetermined positions along the length of the grinding roll tyre 15 or 16. The design of having a scanning sensor 21 and alignment sensor 29 on the wear detection apparatus 20, and a distinct reference mark 19 (or marks) on the grinding roll tyre 15 or 16 is particularly advantageous in that the system provides multiple reference points for detecting surface variations of the grinding roll tyre which, as mentioned, may be caused by vibrations or grinding roll skew in use. Such an effect could not be achieved if, for example, the scanning sensor, alignment sensor and reference point were to be provided from the same point, or substantially the same point above the grinding roll.

[089] An alternative schematic of a grinding roll tyre is shown in Figure 4, wherein the reference mark 19 includes two cylindrical projections, one at each of the longitudinal ends of the grinding roll tyre 15, where the projections have diameters less than the grinding roll such that the reference mark 19 is recessed to the grinding roll surface. While not shown, this cylindrical projection may also include continuous or non-continuous projections or indentations on its surface to assist with determining the relative location or alignment position.

[090] While not shown, in such an arrangement, the apparatus 10 may feature two alignment sensors 29, each alignment sensor corresponding to one of the reference marks 19. This could provide an advantage in allowing the real-time measurement monitoring of alignment deviations by the controller 22 or the processor 40. Alternatively, the apparatus 10 may feature one alignment sensor 29 which is adapted to move along the rail 26 (or on an independent rail) to detect both reference marks 19 at the ends of the grinding roll tyre 15. [091] The distancing of the reference mark 19 away from the crushing area 14

(and also recessed relative to the outer surfaces of the tyres 15, 16) may be particularly advantageous in that there is a reduced risk of the reference mark being obscured or damaged in normal use. Moreover, this design provides a reference point that can be used to determine a roller surface diameter (including any build-up of an autogenous wear layer), and the use of two projections on either side of the grinding roll tyre provides two distanced reference points to easily calculate alignment deviations for correction. These measured distances can also be used to ascertain any skew relative to the longitudinal axis, thereby allowing the measured distances of grinding studs 18 to be compensated for any skew to create the true height of the grinding studs 18.

[092] The reference mark 19 serves a further purpose in providing for the apparatus 20 to scan a surface section of one or more complete revolutions of the roll tyre - for example, the controller 22 may be configured to scan the grinding roll tyre 15 or 16 at each scanning position for one or more complete revolutions by using the reference mark 19 to determine each revolution. Scans of multiple complete revolutions may be averaged to account for any variations caused by, for example, dust or particulate matter in the path of the scanning sensor 21 or residual matter caught on or between the grinding studs 18. As described above, a plurality of circumferential surface section scans may also be processed by the controller 22 and/or the processor 40 to create a composite scan of the entire circumference of the grinding roll tyre 15 or 16 and construct a topology of the entire surface. This surface topology may then be interpreted to determine an overall surface wear status of the grinding roll tyre 15 or 16, thereby indicating whether maintenance of the grinding studs 18 is required.

[093] While the preferred embodiments of the invention have been described in relation to a high-pressure grinding roll apparatus only, it will be appreciated that alternative embodiments toward other grinding roll assemblies, for example a standard grinding roll assembly without a hydraulic actuator, may be envisioned. [094] In the above description, various simplifications have been made for ease of understanding. For example, in Figure 3, only three scanning positions 31 , 32, 33 are illustrated. In other embodiments, a higher or lower number of scanning positions may be provided. Furthermore, in other embodiments, a single scanning window 28 may be provided for a substantial length of the longitudinal axis 27, and the scanning sensor 21 may continuously scan across the single scanning window 28.

[095] In other embodiments, only a single wear detection apparatus 20 may be used, or more than two instances of wear detection apparatus 20 may be used. The one or more wear detection apparatus 20 may be located in a different position to those illustrated.

[096] Throughout this specification and the claims which follow, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Furthermore, unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[097] Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, other example embodiments include from the one particular value and/or to the other particular value, or to any singular value or value range between the two mentioned values. Moreover, ranges may be expressed herein as “more than”, “more than or equal to”, “less than” or “less than or equal to” a particular value. When such a range is expressed, other example embodiments include any singular value or subset value range that lies within the initial value range. [098] Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. For example, it will be appreciated that many combinations, alterations, modifications, variations and substitutions will be apparent to those skilled in the art without departing from the scope of the present invention, and it is intended for this application to embrace all such combinations, alterations, modifications, variations and substitutions. Moreover, wherein specific articles are mentioned which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[099] The preceding description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment, or any aspect described above, may be combined with one or more features of the other embodiments or other aspects of the invention. In addition, any single feature or combination of features in any of the embodiments or aspects of the invention may constitute additional embodiments.

Reference numerals

High-pressure grinding roll apparatus 10

Movable grinding roll 11

Fixed grinding roll 12

Hydraulic actuator 13

Crushing area 14

Movable grinding roll tyre 15

Fixed grinding roll tyre 16

Grinding studs 18

Reference mark 19

Wear detection apparatus units 20

Laser scanning sensor 21

Controller 22

Housing 23

Carriage 25

Rail 26 Longitudinal axis 27 Scanning windows 28 Alignment sensor 29 Scanning surface section 31a Scanning surface section 32a Scanning surface section 33a External processor 40