EP-4735180-A1 - A SENSING ARRANGEMENT FOR A STIRRED MILL AND A METHOD OF SENSING IN A STIRRED MILL

Abstract

A sensing arrangement for a stirred mill is disclosed having a mill shell defining an internal grinding chamber, and a stirrer for rotation within the grinding chamber. The sensing arrangement may comprise a plurality of acoustic and/or vibration sensors mounted on an external surface of the mill shell that are responsive to sounds and/or vibrations within the grinding chamber to generate a signal input, and a processing arrangement for receiving the signal input from the at least one acoustic and/or vibration sensor. The plurality of sensors may be spaced apart in an axial direction of the stirrer. The processing arrangement may generate a processing output on the shape and/or dimension of the stirrer or a processing output on the dynamic height of grinding media within the mill.

Inventors

• MARTINS, SUDARSHAN

Assignees

• Metso USA Inc.

Dates

Publication Date

20260506

Application Date

20230630

Claims (20)

1. 1 . A sensing arrangement for a stirred mill comprising a mill shell defining an internal grinding chamber, and a stirrer for rotation within the grinding chamber, the sensing arrangement comprising: at least one acoustic and/or vibration sensor mounted on an external surface of the mill shell in use, the at least one sensor being responsive to sounds and/or vibrations within the grinding chamber to generate a signal input; and a processing arrangement for receiving the signal input from the at least one acoustic and/or vibration sensor and utilizing a relationship, between the signal input sensed by the at least one acoustic and/or vibration sensor and a configuration and/or dimension of at least a part of the stirrer, to generate a processing output comprising information on the shape and/or dimension of the stirrer.
2. 2. A sensing arrangement for a stirred mill according to claim 1 , wherein the at least one acoustic and/or vibration sensor comprises a plurality of acoustic and/or vibration sensors.
3. 3. A sensing arrangement for a stirred mill according to claim 2, wherein the acoustic and/or vibration sensors of the plurality of acoustic and/or vibration sensors are spaced apart from each other on the external surface in a direction corresponding to an axial direction of the stirrer.
4. 4. A sensing arrangement for a stirred mill according to any one of claims 1 to 3, wherein the sensing arrangement is for a stirred mill in which the stirrer comprises a screw agitator having a screw axis and a blade for rotation within the grinding chamber.
5. 5. A sensing arrangement for a stirred mill according to claim 4, wherein said at least a part of the stirrer comprises at least one radially outer part of the blade.
6. 6. A sensing arrangement for a stirred mill according to any one of claims 1 to 3, wherein the sensing arrangement is for a stirred mill in which the stirrer comprises a shaft and a plurality of discrete structural elements which extend outwardly from the shaft for rotation within the grinding chamber.
7. 7. A sensing arrangement for a stirred mill according to any one of claims 1 to 6, wherein the processing output resulting from the signal input of the at least one sensor provides information on a change in the shape and/or dimension of the stirrer resulting from use of the mill over a length of time, which provides a measure of wear over the length of time.
8. 8. A sensing arrangement for a stirred mill according to any one of claims 1 to 7, wherein the at least one acoustic and/or vibration sensor comprises a plurality of acoustic and/or vibration sensors, and the processing output resulting from the signal inputs of the plurality of sensors provides a measure of wear along the length of the stirrer.
9. 9. A sensing arrangement for a stirred mill according to any one of claims 1 to 8, wherein the processing output comprises a measure of the distance between at least one part of the stirrer and an inner surface of the mill shell (R tank - R max stirrer).
10. 10. A sensing arrangement for a stirred mill according to any one of claims 1 to 9, wherein the at least one acoustic and/or vibration sensor comprises a plurality of acoustic and/or vibration sensors, and the processing output comprises a measure of the distance between a plurality of parts of the stirrer and an inner surface of the mill shell (R tank - R max stirrer) at a position of each acoustic and/or vibration sensor.
11. 11. A sensing arrangement for a stirred mill according to claim 9 or claim 10, wherein an increase in the distance between said part of the stirrer and the inner surface (R tank - R max stirrer) over the length of time provides a measure of wear of the stirrer.
12. 12. A sensing arrangement for a stirred mill according to any one of claims 1 to 11 , wherein the processing output generated by the processing arrangement represents an amount of acoustic and/or vibration energy from the mill sensed by an acoustic and/or vibration sensor, and a decrease in the amount of acoustic and/or vibration energy over time indicates an increase in the distance between a radially outer part of the stirrer and an inner surface of the mill shell.
13. 13. A sensing arrangement for a stirred mill according to any one of claims 1 to 12, wherein the at least one sensor senses sounds and/or vibrations generated within the grinding chamber periodically, and/or substantially continuously, and the signal inputs from the at least one sensor are transmitted periodically, and/or substantially continuously, to the processing arrangement.
14. 14. A sensing arrangement for a stirred mill according to any one of claims 1 to 13, wherein a plurality of acoustic and/or vibration sensors are arranged substantially in a line along the external surface of the mill shell.
15. 15. A sensing arrangement for a stirred mill according to any one of claims 1 to 14 wherein the at least one acoustic and/or vibration sensor comprises at least four acoustic and/or vibration sensors.
16. 16. A sensing arrangement for a stirred mill according to any one of claims 1 to 15, wherein the processing arrangement comprises a computer that is positioned spaced away from the sensor.
17. 17. A sensing arrangement for a stirred mill according to any one of claims 1 to 16, wherein the signal input is transmitted wirelessly to the processing arrangement.
18. 18. A sensing arrangement for a stirred mill according to any one of claims 1 to 17, wherein the processing output is transmitted from the processing arrangement to one or more operating or monitoring personnel over a computer network, and wherein the processing output is presented visually or audibly.
19. 19. A method of sensing a change in a stirrer within a stirred mill comprising a mill shell defining an internal grinding chamber, and a stirrer mounted for rotation within the grinding chamber, the method comprising: sensing acoustic and/or vibration energy within the grinding chamber, by means of at least one acoustic and/or vibration sensor mounted on an external surface of the mill shell, during operation of the mill, to generate a signal input; forwarding the signal input sensed by the at least one acoustic and/or vibration sensor to a processing arrangement; and processing the signal input received from the at least one acoustic and/or vibration sensor using a relationship between the signal input sensed by the sensor and a shape and/or dimension of the blade to generate a processing output comprising information on the shape and/or dimension of at least a part of the stirrer.
20. 20. A method of sensing a change in a stirrer within a stirred mill according to claim 19, wherein the stirrer comprises a screw agitator having a screw axis and a blade for rotation within the grinding chamber.

Description

A SENSING ARRANGEMENT FOR A STIRRED MILL AND A METHOD OF SENSING IN A STIRRED MILL FIELD This invention relates generally to a sensing arrangement for a stirred mill and a stirred mill including the sensing arrangement. It also extends to a method of sensing in a stirred mill. The invention relates particularly to a stirred mill that is a vertical mill or a vertical tower mill (VTM) and it will be convenient to hereinafter describe the invention with reference to this example application. However, it also relates to a HIGmill™ and a Stirred Media Detritor (SMD) mill. Yet further, it relates to a horizontal stirred mill, or an inclined stirred mill, and it is to be clearly understood that the invention applies to all forms of stirred mills. DEFINITIONS In this specification, the term ‘comprising’ is intended to denote the inclusion of a stated integer or integers, but not necessarily the exclusion of any other integer, depending on the context in which that term is used. This applies also to variants of that term such as ‘comprise’ or ‘comprises’. BACKGROUND One example of a known type of stirred mill comprises a mill shell defining an internal grinding chamber. A stirrer or agitator, which, in this example, is in the form of an agitator screw, is mounted within the grinding chamber for agitating contents within the grinding chamber. The agitator screw is driven by an external drive arrangement that is mounted co-axially with the agitator. In this example of a vertical mill, the drive arrangement is mounted in proximity to the mill shell. In use, the mill typically contains a grinding media, e.g. in the form of a ball charge comprised of grinding balls. The mill with its contained grinding media is used to grind a slurry of mineralcontaining particles to reduce the size of the particles and thereby liberate valuable mineral within the particles. Sometimes dry grinding, rather than grinding a slurry of particles, is preferred or required. Rotation of the agitator screw lifts and moves the particles and the grinding media, and this progressively reduces the size of the mineral-containing particles within the mill. Once the mineral-containing particles have been reduced to fines, they tend to rise up through the grinding chamber and be drawn off. The agitator screw comprises a shaft and a blade extending radially outward away from the shaft that makes contact with the particles, and the grinding balls. In one form, the blade may be in the form of a helical spiral although it must be appreciated that other types or configurations of blades may also be used. The blade has a wear surface that is exposed to significant wear during operation of the mill. In some stirred mills, the blade comprises an underlying blade base and a set of replaceable wear liners mounted over the blade base to deal with this wear. The replaceable wear liners wear down over time and need to be replaced periodically. Further, other stirred mills, instead of having a blade base with a replaceable wear liner mounted thereon, have a sacrificial stirrer. These stirrers are progressively worn down in use and replaced at their end of life. A H IGm ill™ is an example of such a mill. Stirrers, including sacrificial stirrers, may be of forms other than agitator screws. For example, some mills, including the HIG mill and the SMD mill, may have a stirrer configured with a central shaft and a plurality of posts (sometimes called ‘pins’) or other structures extending outwardly therefrom towards the sides of the internal grinding chamber. One example of an existing stirred mill is the VERTIMILL® vertical mill manufactured and produced by the Applicant which is shown in Figures 1 and 2 of the drawings. This mill has a stirrer in the form of an agitator screw with a vertically extending axis driven by a co-axial drive arrangement mounted on top of the mill shell. The VERTIMILL® is extremely effective at comminution and its utilization and uptake in mineral processing circuits has steadily increased over the past 10 years. The VERTIMILL® is primarily used for grinding, particularly fine grinding, to reduce the size of mineral containing particles to liberate minerals. The VERTIMILL® has also proved to be very efficient for regrinding, secondary and tertiary grinding, and lime slaking applications. In Figures 1 and 2, a lower region of the wall of the mill shell has been removed to open up the mill shell and provide visibility of the internal grinding chamber. An agitator screw is received within the grinding chamber comprising an axial shaft and a blade that extends radially outward from the axial shaft and along the axial shaft with a helical spiral. Figure 2 shows a grinding media in the form of a ball charge in the internal grinding chamber. The blade extends in a helical spiral around the screw axis as shown in Figures 1 and 3. During operation of the vertical mill, rotation of the blade lifts the grinding balls and the mineral particles, and it als