Lateral wall assembly sensing

Abstract

Lateral wall assembly sensing system 10 comprising a base plate 30, wear resistant layer 32 having a rear surface 42 mounted on a front side 26 of the base plate 30, and a front surface 40 for mountin

Description

FIELD OF INVENTION The invention relates to improvements in or relating to a lateral wall assembly for use with a dual roll grinding machine, such as a high pressure grinding roller (HPGR), and particularly to sensing wear of such a lateral wall assembly. BACKGROUND OF THE INVENTION In HPGR machines, the material to be comminuted is discharged into a gap between two rollers rotating in opposite directions. The material to be ground is drawn into the roller gap by the rollers then compacted and crushed. For optimum crushing, the roller gap should be uniformly filled with material to be ground along the axial length of the roller gap (which is the axial length of the rollers). One problem that occurs is when the material being ground emerges laterally from the grinding gap without having passed through the grinding gap. This leads to a reduction in the throughput of the HPGR and an increase in the grinding cycle, which is associated with a large expenditure of energy. To prevent such lateral loss of material, a boundary is typically provided at each side of the roller gap to prevent material escaping therefrom. One type of boundary is a fixed lateral wall assembly, i.e. it does not rotate with the rollers. One example of a fixed lateral wall is described in WO 2011 / 051117 A1 to KHD Humboldt Wedag GmbH, such a lateral wall assembly is also called a cheek plate. Lateral wall assemblies need to be able to handle the high grinding pressure and abrasive materials that act on those assemblies, which leads to excessive wear or even breakage of one or more parts or all of the lateral wall assemblies. Premature failure of a lateral wall assembly due to wear incurs significant costs in time and money as HPGRs are intended to run continuously between service intervals and their grinding efficiency depends on the endurance of the lateral wall assembly. It would be advantageous if a sensing system could be provided that measures the wear on a lateral wall assembly, thereby allowing the operating life of the lateral wall assembly to be predicted accurately. It is among the objects of an embodiment of the present invention to overcome or mitigate one or more of the above disadvantages or other disadvantages of the prior art, or to provide a useful alternative. SUMMARY OF THE INVENTION This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify 2 indispensable features of the claimed subject matter, nor is it intended for use as an aid in limiting the scope of the claimed subject matter. In this application relative terms are used, such as front, rear, up, down, etc., only for ease of the description and understanding of the embodiments, not by way of limitation. Ordinal numbers (first, second, third, etc.) are assigned arbitrarily herein, and are used to differentiate between parts, and do not indicate a particular order, sequence or importance. According to a first aspect there is provided a lateral wall assembly sensing system comprising: (i) a base plate; (ii) a wear-resistant layer having a rear surface mounted on a front side of the base plate and a front surface for mounting in close proximity to an edge of a grinding roller; (iii) a sensor mounted in a cavity defined in the base plate and operable to measure a distance from the sensor to a front surface of the wear-resistant layer; (iv) a collector coupled to the sensor for ascertaining a wear amount based on the received sensor distance measurement. Optionally, the system further comprises a receiver coupled to the sensor and the collector for receiving signals from the sensor and relaying them to the collector. Optionally, the cavity is defined in a rear side of the base plate. Optionally, the combination of the base plate and the wear-resistant layer may comprise a wear assembly. Optionally, the system further comprises a backing plate onto which the base plate may be removably mounted. Optionally, the sensor cavity may be closed by an epoxy, elastomer, or other suitable material. Optionally, the sensor comprises an ultrasonic sensor. Optionally, the system comprises a plurality of sensors, each mounted in a base plate cavity, and each sensor being opposite a different portion of the wear-resistant layer at which wear is to be ascertained. Optionally, the collector is coupled to a plurality of sensors, and may create a topographical map of wear on the front surface of the wear-resistant layer. Optionally, the base plate defines two concave edges generally symmetric about a longitudinal centre line thereof. The concave edges may each have a radius approximately equal to a radius of the respective roller against which that part of the wear-resistant layer is mounted. Optionally, the base plate comprises a central wear region extending along a lower portion of the longitudinal centre line. Optionally, a plurality of sensors are aligned along the longitudinal centre line. Optionally, a plurality of sensors are disposed in pairs on opposing sides of the longitudinal centre line. Optionally, the wear-resistant layer may comprise a plurality of wear-resista nt elements, such as tiles. The wear-resistant layer may be mounted to the base plate using 5 brazing, welding, gluing, or any other convenient technique. Optionally, the cavity defined in the rear side of the base plate includes an aperture extending through to the front side of the base plate such that material (such as brazing) used to couple the wear-resistant layer to the front of the base plate protrudes through the aperture and into contact with the sensor mounted in the cavity. This may provide a more 10 accurate measurement of the distance from the sensor to the front surface of the wear-res ista nt layer. Optionally, the receiver and the collector may be combined in a single module. It will now be appreciated that this aspect has the advantage of being able to measure the amount of wear, and optionally the rate of wear, of a wear-resistant layer, thereby 15 enabling better management of service intervals for the grinding roller on which the lateral CO wall assembly sensing system is mounted. C\l *• M Embodiments of this aspect are able to measure a thickness of a target material through a brazed (or otherwise bonded) support material, where the materials are of different 1 compositions or thicknesses, and the brazing (or bonding) may not be homogenous. CO 20 According to a second aspect there is provided a grinding roller machine comprising 1 at least one lateral wall assembly sensing system according to the first aspect, mounted on a side of a pair of rollers. Optionally, a pair of lateral wall assembly sensing systems may be provided, one mounted on each opposing side of the pair of rollers. 25 The grinding roller may comprise a pair of counter-rotating rollers defining the roller gap therebetween and being supported in a machine frame. The grinding roller may comprise a high pressure grinding roller (HPGR), in which one roller is fixed in position, and the other roller is urged towards the fixed roller at a constant pressure. 30 Each lateral wall assembly may straddle an end of the roller gap. According to a third aspect there is provided a method of measuring wear of a wearresistant layer on a lateral wall assembly, the method comprising: (i) using a sensor to measure a distance from a base plate to a front surface of a wear-resistant layer at each of a plurality of different points over the front surface; (ii) transmitting the measured distance 35 from the sensor to a collector; and (iii) using the collector to ascertain a wear amount of the front surface based on the received sensor distance measurements. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a simplified exploded perspective view of a lateral wall assembly sensing system in accordance with one embodiment of the present invention; Fig. 2 is a front perspective view of one part (the tip wear assembly) of the lateral wall assembly of Fig. 1; Fig. 3 is a front elevation view of the lateral wall assembly sensing system of Fig. 1, showing parts thereof (wear assemblies) in more detail; Fig. 4 is a simplified side elevation showing a cross section through part of the lateral wall assembly sensing system of Fig 1 showing parts thereof (a wear assembly coupled to a backing plate), and illustrating a mounting method thereof; Fig. 5 is a simplified side elevation showing a cross section through a wear assembly of a lateral wall assembly sensing system similar to that of Fig 1, and illustrating an alternative mounting method therefor; Fig. 6 is a simplified side view of part of an HPGR showing part of one of the lateral wall assemblies mounted on rollers of the HPGR; and Fig. 7 is a simplified side elevation, similar to Fig. 4, but showing an alternative backing plate. DETAILED DESCRIPTION OF EMBODIMENTS Reference is now made to the drawings, and particularly to Fig. 1, which is a simplified exploded perspective view of a lateral wall assembly sensing system 10 in accordance with one embodiment of the present invention. The lateral wall system 10 comprises a lateral wall assembly 12 that is generally symmetrical about a longitudinal centre line 14, and comprises a backing plate 20 on which a plurality of wear assemblies 22 are mounted, but shown separated in the exploded perspective view of Fig. 1. The backing plate 20 couples the lateral wall assembly 12 to a high pressure grinding roll (HPGR) machine (not shown) via conventional mounting portions 24 (which may have a different shape to that shown in Fig. 1). The backing plate 20 has a front surface 26 (visible in Fig. 1) and a rear surface 28 opposite the front surface 26. The backing plate 20 includes a plurality of apertures 29 (best seen in Fig. 4) through which bolts 31 (best seen in Fig. 4) may be inserted to secure the wear assemblies 22 to the front surface 26 in a conventional manner. In this embodiment, six wear assemblies 22 are provided. As best seen in Figs. 2 and 4, which is an enlarged perspective view of a tip wear assembly 22a, each wear assembly comprises a base plate 30 on which a wear-resistant layer 32 is mounted. In this embodiment, the wear-resistant layer 32 comprises a plurality of individual tungsten carbide tiles coupled to the base plate 30 by a brazing layer 33 (best seen in Figs. 4 and 5), but in other embodiments a different wear material (such as silicon carbide or silicon nitride) or a different form factor (such as inserts or a plate instead of tiles), or a different coupling method (such as welding or gluing, or other bonding technique) may be used. In other embodiments, the wear-resistant layer 32 may be formed, for example, by deposition, cladding, infiltration, or the like. The base plate 30 is not intended to be used as a wear layer. Once the wear-resistant layer 32 has worn down, the wear assembly 12 should be replaced. To facilitate this, the lateral wall assembly sensing system 10 provides a mechanism for detecting the amount of wear experienced by the wear-resistant layer 32, as will be described in more detail below. The tip (or stub) wear assembly 22a is mounted at a lower part (a stub portion) 34 of the lateral wall assembly 12 such that, when mounted on an HPGR, the stub portion 34 is aligned with the narrowest part of the gap between the HPGR rollers. Unlike the other wear assemblies 22b to 22f, the tip wear assembly 22a includes a mounting bracket 36 extending upwards from an upper portion of the base plate 30a. The mounting bracket 36 engages with, and depends from, a protrusion (not shown) on a rear surface of the stub portion 34. In addition to the tip wear assembly 22a, there is a lower wear plate assembly 22b, a centre wear plate assembly 22c, and an inlet wear plate assembly 22d. These four wear plate assemblies 22a to 22d are all centred (vertically aligned) on the longitudinal centre line 14. Two other wear plate assemblies 22 are provided: a left sealing plate assembly 22e and a right sealing plate assembly 22f. These sealing plate assemblies 22e,f are mounted on either side of the centre wear plate assembly 22c, and, when the lateral wall assembly 12 is mounted on an HPGR, abut against the edges of the HPGR rollers. In each wear plate assembly 22, the wear-resista nt layer 32 has a front surface 40 that is closest to an HPGR roller, and a rear surface 42 that is coupled to a front surface 44 of the base plate 30. The rear surface 46 of the base plate 30 is coupled to the front surface 26 of the backing plate 20. The backing plate 20 (in this embodiment the front surface 26 of the backing plate 20) defines one or more cavities 50 in which one or more ultrasonic receivers 52 are mounted, such that each receiver 52 is flush or recessed with respect to the front surface 26. An epoxy or resin may be used to seal the receiver 52 inside the cavity 50. In this embodiment there are six cavities 50a to 50f, one for each wear assembly 22a to 22f, and there is one receiver 52 in each cavity 50. In other embodiments, multiple receivers may be 6 located in a single cavity. In this embodiment, each cavity 50 is formed by bolting a cover plate 53 over an aperture extending through the backing plate 20, thereby creating the cavity 50, but in other embodiments, the cavity 50 may comprise a recess formed in the backing plate 20 without requiring a cover plate 53. The cover plate 53 provides physical access to the receiver 52, if required, without dismounting the lateral wall assembly 12 from an HPGR. Each receiver 52 is in proximity to, and aligned with, a corresponding ultrasonic sensor 54 mounted in a cavity 56 in the rear surface 46 of the base plate 30. For example, receiver 52d is aligned with sensor 54d in the inlet wear plate assembly 22d. This allows the sensor 54d to measure the distance from the sensor 54d to the front surface 40d of the wearresistant layer 32d. By taking measurements at a plurality of locations across the front surface 40, the amount of wear experienced by the wear-resistant layers 32 can be calculated. If the time at which these measurements are taken is also recorded, then the wear rate at each location can be calculated. A collector device 60 is provided outside the lateral wall assembly 12 and is connected to the receivers 52 in a wired or wireless manner to collect the measurements recorded by each receiver 52. The collector device 60 communicates with an app, an edge computing device, or the cloud, to relay the measurements thereto for analysis and processing. The collector device 60 can be used to facilitate configuration of the sensors 54 so that the sensors 54 are correctly mapped to their physical location on the lateral wall assembly 12. Where a wired connection is used, the cover plate 53 may include a wiring aperture (preferably protected by a grommet) through which a cable connecting the collector device 60 to the receivers 52 is routed. Suitable ultrasonic receivers 52, sensors 54, and collector devices 60 are included in the wireless and non-destructive (WAND) system available from Inductosense Limited °f Unit 3, Kings Business Park, Feeder Road, St Philips, Bristol, BS2 0TZ. Other types of sensors may also be suitable. Reference is now made to Fig. 5, which is a simplified side elevation showing a crosssection through a wear assembly 22’ of a lateral wall assembly sensing system similar to that of Fig 1, and illustrating an alternative mounting method therefor. In particular, the base plate 30’ defines a bonding aperture 62 therethrough. The wear-resistant layer 32 is identical to that of Fig. 1, but the brazing layer 33’ couples the rear surface 42 of wear-resistant layer 32 directly to the front surface 44’ of base plate 30’ and also a front surface of ultrasonic sensor 54, via the bonding aperture 62. In other words, the brazing layer 33’ extends through the bonding aperture 62 to provide a continuous metallic connection between the wear-resistant 7 layer 32 and the ultrasonic sensor 54. This may provide a more accurate measurement of the distance from the ultrasonic sensor 54 to the front surface 40 of wear-resistant layer 32. Reference is now made to Fig. 6, which is a simplified side view of part of an HPGR 68 having one of the lateral wall assembly sensing systems 10 mounted adjacent to rollers 70a,b thereof. The rollers 70a,b define a roller gap 72 therebetween. Ore to be ground enters the roller gap 72 from above, as illustrated by arrow 74. During operation of the HPGR 68, the wear assemblies 22, particularly the wear-resistant layer 32, wears away. The thickness of each of these wear assemblies 22 is detected by the collector device 60 (either continuously or at regular intervals), using sensors 54 and receivers 52. This information can be used to ascertain the wear rate of the different wear assemblies 22 and to predict when the lateral wall assembly 12 needs to be replaced. This information may also be used to create a topographical map of wear on the front surface 40 of the wear-resistant layer 32. Such a topographical map may be displayed on a graphical user interface to a user of an app or a computer. Reference is now made to Fig. 7, which is a simplified side elevation, similar to Fig. 4, but showing an alternative backing plate 20’. Backing plate 20’ differs from backing plate 20 in that there is no cover plate 53. Instead, the backing plate 20’ includes a through aperture 76 in which a cable 78 is threaded to couple the receiver 52 to the collector device 60. It should now be appreciated that these embodiments have the advantage that it is possible to measure the wear and the wear rate of each of the wear assemblies 22. Various modifications may be made to the above embodiments within the scope of the present invention. For example, in other embodiments, a different wear-resistant layer may be used. In other embodiments, the wear assemblies 22 may not be mounted symmetrically on the backing plate 20 about the centreline 14. For example, a wear assembly 22 may be different in size or shape to other wear assemblies 22; and the positioning of wear assemblies 22 on the backing plate 20 may be influenced by the size and weight of each wear assembly 22. Although a plurality of wear assemblies are illustrated in the above embodiment, in other embodiments there may be a single wear assembly. In the foregoing description of certain embodiments, specific terminology has been used for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "upper" and "lower", "above" and "below" and the like are used as words of convenience to provide reference points and are not to be construed as limiting 8 terms, nor to imply a required orientation of the seal assembly. The word “or” is used to indicate that one or more of the words listed may be present, unless the context requires the disjunctive use. In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of’. A corresponding meaning is to be attributed to the corresponding words “comprise", "comprised" and "comprises" where they appear. 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 may be combined with one or more features of the other embodiments. In addition, any single feature or combination of features in any of the embodiments may constitute additional embodiments. In addition, the foregoing describes only some embodiments of the inventions, and alterations, modifications, additions and / or changes can be made thereto without departing from the scope of the disclosed embodiments, the embodiments being illustrative and not restrictive. List of reference numerals: Lateral wall assembly sensing system 10 Lateral wall assembly 12 Longitudinal centre line 14 Backing plate 20, 20’ Wear assemblies 22 Mounting portions 24 Front surface (of backing plate) 26, 26’ Rear surface (of backing plate) 28, 28’ Apertures (in backing plate) 29, 29’ Bolts (in backing plate) 31 Base plate 30, 30’ Wear-resistant layer 32 Brazing layer 33, 33’ Lower part (stub portion) 34 Mounting bracket 36 Front surface (of wear-resistant layer) 40 Rear surface (of wear-resistant layer) 42 Front surface (of base plate) 44, 44’ Rear surface (of base plate) 46 Backing plate cavities 50 Ultrasonic receivers 52 Cover plate 53 Ultrasonic sensor 54 5 Base plate cavity 56 Collector device 60 Bonding aperture 62 HPGR68 HPGR rollers 70a,b 10 Roller gap 72 Arrow 74 Backing plate aperture 76 Cable 78

Claims

1. 2.3.4.5.6.7.8.9.A lateral wall assembly sensing system comprising: (i) a base plate; (ii) a wear-resistant layer having a rear surface mounted on a front side of the base plate and a front surface for mounting in close proximity to an edge of a grinding roller; (iii) a sensor mounted in a cavity defined in the base plate and operable to measure a distance from the sensor to a front surface of the wear-resistant layer; (iv) a collector coupled to the sensor for ascertaining a wear amount based on the received sensor distance measurement.The lateral wall assembly sensing system of claim 1, wherein, the system further comprises a receiver coupled to both the sensor and the collector for receiving signals from the sensor and relaying them to the collector.The lateral wall assembly sensing system of claim 1 or 2, wherein the combination of the base plate and the wear-resistant layer comprises a wear assembly, and the cavity is defined in a rear side of the base plate.The lateral wall assembly sensing system of claim 1 to 3, wherein the system further comprises a backing plate onto which the base plate is removably mounted.The lateral wall assembly sensing system of any preceding claim, wherein the sensor cavity is closed by an epoxy or elastomer.The lateral wall assembly sensing system of any preceding claim, wherein the sensor comprises an ultrasonic sensor.The lateral wall assembly sensing system of any preceding claim, wherein, the system comprises a plurality of sensors, each mounted in a base plate cavity, and each sensor being opposite a different portion of the wear-resistant layer at which wear is to be ascertained.The lateral wall assembly sensing system of any preceding claim, wherein the collector is coupled to a plurality of sensors, and creates a topographical map of wear on the front surface of the wear-resistant layer.The lateral wall assembly sensing system of any preceding claim, wherein a plurality of sensors are aligned along a longitudinal centre line thereof.

10. The lateral wall assembly sensing system of claim 8, wherein a plurality of sensors are disposed in pairs on opposing sides of the longitudinal centre line.

11. The lateral wall assembly sensing system of any preceding claim, wherein the wear-resistant layer comprises a plurality of wear-resistant elements. 5 12. The lateral wall assembly sensing system of any preceding claim, wherein the cavity defined in the rear side of the base plate includes an aperture extending through to the front side of the base plate such that material used to couple the wear-resistant layer to the front of the base plate protrudes through the aperture and into contact with the sensor mounted in the cavity. 10 13. A grinding roller machine comprising at least one lateral wall assembly sensing system according to any preceding claim, mounted on one side of a pair of rollers. co CM i— 15 14. A method of measuring wear of a wear-resistant layer on a lateral wall assembly, the method comprising: (i) using a sensor to measure a distance from a base plate to a front surface of a wear-resistant layer at each of a plurality of different points over the front surface; (ii) transmitting the measured distance from the sensor to a collector; and (iii) using the collector to ascertain a wear amount of the front surface based on the received sensor distance measurements.

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