Grinding Method and System with Material Inlet Detection

Abstract

A method for grinding feed material (1) in the form of particulate bulk material is disclosed. In the process, particle sizes of the feed material (1) are detected, and the feed material (1) is ground in a mill (3) on the basis of at least one manipulated variable. The at least one manipulated variable is modified when the proportion of small particle sizes in the detected particle sizes increases. A system for grinding feed material (1) in the form of particulate bulk material is also disclosed.

Claims

1. A method for grinding feed material (1) in the form of particulate bulk material, including the steps of: detecting particle sizes of the feed material (1), grinding the feed material (1) in a mill (3) on a basis of at least one manipulated variable, and modifying the at least one manipulated variable if a proportion of small particle sizes in the detected particle sizes of the feed material (1) increases.

2. The method according to claim 1, further comprising: calculating a parameter which is indicative of the proportion of small particle sizes, and modifying the at least one manipulated variable on the basis of the parameter.

3. The method according to claim 2, wherein the parameter is calculated by dividing a determined particle number by a maximum number of particles detectable by a feed material detection device.

4. The method according to claim 2, wherein the parameter is calculated on the basis of a diameter for each detected particle, wherein the diameter of each detected particle is calculated based on a projected area of the detected particle, and wherein the parameter is calculated by means of a division of a sum of the projected areas of the particles with a diameter of up to a selected mesh size by a sum of the projected areas of all particles.

5. The method according to claim 2, wherein the parameter is calculated from a cumulative distribution function with respect to the particle sizes.

6. The method according to claim 5, wherein the cumulative distribution function is volume-based, and wherein the volume-based cumulative distribution function has a diameter limit value as a function argument, and a quotient of a sum of the volumes of all detected particles having a diameter smaller than the diameter limit value divided by the sum of the volumes of all detected particles as a function value, wherein the parameter is the diameter value where the function value of the cumulative distribution function corresponds to a fixed shortfall proportion.

7. The method according to claim 1, wherein the grinding is performed by rotation of a grinding plate (4) relative to grinding rollers (5) about a central axis (100) of the grinding plate (4), so that the grinding rollers (5) roll on a grinding path of the grinding plate (4) about a roller rotation axis.

8. The method according to claim 1, wherein the modification of the at least one manipulated variable causes a reduction of a drive rotational speed of the mill (3), in particular a rotational speed of a grinding plate (4).

9. The method according to claim 1, wherein the modification of the at least one manipulated variable causes a reduction of a contact force of at least one rolling element (5) of the mill (3).

10. The method according to claim 1, wherein the modification of the at least one manipulated variable causes a reduction of a mass flow of the feed material (1).

11. The method according to claim 1, wherein the modification of the at least one manipulated variable causes an increase of an amount of water introduced into a grinding space of the mill (3).

12. The method according to claim 1, further comprising: detecting a vibration generated by the grinding, and storing a time history of at least one parameter in view of the vibration, at least one parameter in view of the detected particle sizes, and at least one parameter in view of a grinding power as an operational data set.

13. A system for grinding feed material (1) in the form of particulate bulk material, comprising: a feed conveyor (2), a bulk material mill (3) with a vibration sensor (20) configured to detect vibrations during a grinding operation, a feed material detection device (11) configured to detect at least one parameter of the feed material (1) on the feed conveyor (2), and a control unit (15) configured to control the bulk material mill (3) on a basis of the at least one detected parameter and the detected vibrations.

14. The system according to claim 13, wherein the at least one parameter of the feed material (1) is a particle size of the feed material.

15. The system according to claim 13, wherein the at least one parameter of the feed material (1) is a proportion of small particle sizes.

16. The system according to claim 13, wherein the control unit (15) includes a data storage, wherein the control unit (15) is configured to store in the data storage an operational data set including a time history of the at least one parameter of the feed material (1) and at least one parameter relating to the detected vibrations, wherein the control unit (15) is further configured to control the bulk material mill (3) based on the operational data set.

17. The system according to claim 13 , wherein the control unit (15) includes a data connection and is configured for exporting operational data sets, the operational data sets comprising a time history of the at least one parameter of the feed material (1) and at least one parameter relating to the detected vibrations.

18. The system according to claim 13, wherein the control unit (15) is configured to detect at least one parameter of a final product produced by the bulk material mill (3), including a temperature and/or particle sizes of the final product, and to consider the at least one parameter of the final product in the control of the bulk material mill (3).

Description

[0056] The invention will be further illustrated below with reference to exemplary embodiments which are represented in the figures, In the drawings

[0057] FIG. 1 shows a schematic side view of an embodiment of a system according to the invention; and

[0058] FIG. 2 shows a sectional view in the region of the feed material detection device.

[0059] In FIG. 1, a system for grinding feed material in the form of particulate bulk material, in particular particulate rock material or cement raw material, is shown in a schematic side view. Below, an embodiment of the method according to the invention will also be illustrated in this respect.

[0060] The feed material 1 is conveyed on a feed conveyor 2 towards a bulk material mill 3. The bulk material mill 3 includes a grinding plate 4 and a plurality of grinding rollers 5, the grinding plate 4 being rotated about a central axis 100 by means of at least one drive 6, so that the grinding rollers 5 roll on the grinding plate 4. The feed material 1 is ground in the grinding gap between the grinding rollers 5 and the grinding plate 4. The ground feed material 1 is supplied to a classifier 7 by means of an air flow in the outer peripheral region of the grinding plate 4, wherein the classifier lets pass sufficiently finely ground material with the air flow out of the bulk material mill 3 while particles that are too coarse are guided back to the grinding plate 4 and reground again there.

[0061] The grinding rollers are each mounted in a bracket 9 via a rocker arm 8. The contact force of the grinding rollers on the grinding plate can be controlled by a linear final controlling element 10 attached to the rocker arm 8. Above the feed conveyor 2, a feed material detection device 11 is provided. The feed material detection device 11 is shown in detail in FIG. 2. The feed material detection device 11 comprises a camera and two illumination means 13. The illumination means 13 illuminate the feed material 1 present on the feed conveyor 2, and the camera 12 acquires a picture of the feed material 1.

[0062] The data acquired with the camera 12 are transmitted to a camera control unit 14 and evaluated there by means of image processing algorithms. In particular, the number and size of particles in the acquired image are calculated. Starting from this, the proportion of small particle sizes in the detected particle sizes is calculated. If an increase of the proportion of small particle sizes within the totality of the detected particle sizes occurs, this is indicated to a mill control unit 15 which then modifies at least one manipulated variable in view of the control of the mill.

[0063] The feed material detection device 11 is in particular designed to detect the uppermost layer of the feed material piled up on the feed conveyor 2. From the detection of the uppermost layer, the particle size distribution in the total feed material can then be estimated, extrapolated and/or calculated in the camera control unit 14 by means of a system-specific correction value,

[0064] The mill control 15 is in particular data-connected with the linear final control element 10 and can thereby control the contact force of the grinding rollers 5 onto the grinding plate 4. Furthermore, the mill control unit 15 is data-connected with the drive 6 of the grinding plate 4 and can thereby control the rotational speed of the grinding plate 4. The mill control 15 can also be data-connected with a drive 16 of the feed conveyor 2 and thereby control the amount of the feed material 1 supplied to the mill per time. Furthermore, the mill control unit 15 can be data-connected with a water injection device 17 by which water can be injected into the grinding space of the mill 3. Thus, the control unit can control the amount of water introduced into the grinding space of the mill.

[0065] FIG. 2 furthermore represents the more precise construction of a possible feed conveyor 2, wherein in the lateral region, support rolls 18 slightly bent to the top can be provided, so that the conveyor belt 19 of the feed conveyor 2 is shaped concavely transversely to the conveying direction and thus can ensure that no feed material 1 falls down laterally from the feed conveyor 2.

[0066] In particular, a bunker can be arranged upstream of the feed conveyor 2 from which a desired amount of feed material is deposited on the feed conveyor 2. The material bunker can be provided with a load cell to be able to effect the discharge of feed material in a controlled manner.

[0067] A distributing guide can be arranged upstream of the feed conveyor 2 and convey unsuited feed material not onto the feed conveyor, but to a bunker. In particular, a magnetic detector can be arranged upstream of the distributing guide for this which determines whether magnetic material is contained in the feed material. In this case, the distributing guide is activated such that the feed material is not guided to the feed conveyor 2 but into a bunker.

[0068] Furthermore, a vibration sensor 20 can be provided which is designed to detect vibrations during the grinding operation of the bulk material mill 3. In one embodiment, the vibration sensor 20 can be attached, for example, to the rocker arm 8. The vibration sensor can, as an alternative, be attached at the housing of the mill, at the grinding plate 4, at the bearing of the grinding plate 4, or at the bracket 9. In particular, a plurality of vibration sensors can be provided.

[0069] The vibration sensor 20 is data-connected to the mill control unit 15. The mill control unit 15 is designed to control the bulk material mill on the basis of the data of the camera control unit 14 and the vibration sensor 20.