System for in-line estimation of load distribution in a rotary mill

Abstract

A system and method for online estimate of the filling level of balls and loading level in a rotary mills, comprising a set of vibration sensors unit, associated with a magnet to transmit data signals via an antenna to a receiver that receives data signals from the antenna, an antenna, wherein the receiver is connected via optical fiber to a signal processor, which in turn communicates to a control server via a UTP cable, wherein the control server also obtains data from the mill operation to determine the best filling of balls and load; and the operating method.

Claims

1. A system for online estimate of the filling level of balls and loading level in a rotary mill, the system comprising: a signal processor (40) connected to a receiver (30) via optical fiber (35) and an antenna (32) located outside and near said mill (60); a magnet (20) located outside and near said mill (60); a set of vibration sensors unit (10) placed on the mantle of said mill (60), comprising a first processor (13), an antenna (17), a plurality of accelerometers (14) and a plurality of microphones (11), all connected to said first processor (13), wherein said first processor (13) is configured to: register the vibrations produced by the load (63) during the grinding process and measure the sounds from inside the mill (60) by said plurality of microphones (11); produce data corresponding to the average and variance of vibrations of the mill (60); obtain a synchronism signal by the obtained sound; determine the direction of rotation and the quadrant where it should be located the foot (65), and the quadrant where it should be located the shoulder (66) of the load; and transmit data signals by said antenna (17) to said receptor (30) by said antenna (32) and said signal processor (40) is configured to receive said data signals and obtain said data corresponding to the average and variance of vibrations of the mill (60), said synchronism signal and of foot quadrant and shoulder quadrant; a control server (50) configured to communicate with said signal processor (40) via a UTP cable (48), and configured to: obtain data from the operation of the mill (60) as input grain size distribution of fresh ore, tonnage of fresh ore, water supply, rotation speed of the mill (60), refill of ball (62), average power and pressure on the mill (60) bearings; calculate the instantaneous power p(t) consumed by the mill (60) and determining the foot (65) and shoulder (66) of the load (63) of the mill (60); assess the models of foot (65), shoulder (66), power, pressure, wear of liners and of balls (62); iterate the filling values of balls (62) and load (63) within the aforementioned models, and compare the prediction of models with the values measured in the data signals by the system; and determine the level of filling of balls (62) and level of load (63) based on said comparison.

2. The system according to claim 1, wherein the system is installed in the environment of a rotary mill (60); where the set of vibration sensors unit (10) comprises at least two vibration sensors (10, 10′) which are placed on the mantle of the mill (60), equidistant at least at an angle greater than 90°, so that the data signal transmitted through the antenna (17) is only received by the antenna (32) of the receiver (30) from only one of the vibration sensors (10, 10′) during the transmission interval; the magnet (20) located on one side and close to the mantle of the mill (60), allows vibration sensors (10, 10′) passing periodically by the magnet (20) to detect the direction and speed of rotation, allowing to determine the angle for wireless transmission to the receiver (30).

3. The system according to claim 2, wherein the set of vibration sensors unit (10) comprises a pair of magnetic sensors (16) to detect the direction and speed of rotation; providing this information to the first processor (13) as the synchronism signal, which also receives a signal of the state of charge of a battery (15), which feeds the set of vibration sensors unit (10); the plurality of microphones (11), connected to the first processor (13) receive sounds from the inside of the mill (60) for abnormal noise analysis; the plurality of accelerometers (14) connected to the first processor (13) register the vibrations produced by the load (63) during the grinding process; all information received by the first processor (13) is processed and sent by a transmitter (12) to the receiver (30), located near the mill (60), so as to receive a single data stream only from one of the vibration sensors (10, 10′), each time.

4. The system according to claim 1, wherein the receiver (30) sends the information to the signal processor (40) through optical fiber (35), where a converter of optical signals to electrical signals (42) sends electrical signals to a second processor (45) that directs them through the communication unit (46) to the control server (50) through the UTP cable (48), data are periodically sent to the control server (50), to which effect they are previously stored in a storage unit (43), when received by the converter of optical signals to electrical ones (42).

5. The system according to claim 2, wherein the two vibration sensors (10, 10′) are separated in such a way, that only one of them can transmit to the receiver (30), where said transmission is controlled by the first processor (13) which sends a signal to the battery (15) to feed the transmitter (12) only during the transmission interval that each of the vibration sensors (10, 10′) has.

6. The system according to claim 3, wherein the accelerometers (14) have different ranges of operation, so that when there is saturation in any of them, the information is valid in at least one of them, in the understanding that the operating ranges cover the entire spectrum of vibrations produced by the mill (60) during operation.

7. The system according to claim 6, wherein the first processor (13) collects the information from the accelerometers (14) for a number of turns preset and processes this information covering the entire circumference of the mantle of the mill (60) and sends all values during the interval of time available for each sensor of vibrations (10, 10′); the values obtained allow determining the shoulder (66) and foot (65) of the volume of load in the control server (50).

8. The system according to claim 7, wherein the data obtained by the accelerometers (14) that are processed by the first processor (13), together with those of sound obtained by microphones (11), and the synchronism signal for a predetermined amount of turns, allows the first processor (13) determining the direction of rotation, the quadrant where the foot (65) should be located and the quadrant where the shoulder (66) should be located; with sound intensity it is verified that the quadrants are the right ones; then, the average of amplitude and variance of vibrations are calculated for the entire circumference of the mill and for each turn; then an average between turns is obtained, getting an average and a variance of a turn that represents them all, and the calculations are sent within the transmission time defined before, the results obtained along with the possible quadrants for foot (65) and shoulder (66).

9. The system according to claim 1, wherein the preceding claims allow and also contribute to reduce the variability and variance in the control of processes of milling and concentrating plants that use said rotary mills.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 depicts a block diagram of the electronic system of the invention.

(2) FIG. 2 depicts an isometric view of the electronic system of the invention configured in a mill.

(3) FIG. 3 depicts a side view of the electronic system of the invention configured in a mill.

(4) FIG. 4 depicts a side sectional view of the electronic system of the invention configured in a mill.

(5) FIG. 5 depicts the block diagram of the scanner of vibrations.

(6) FIG. 6 depicts the block diagram of the signal processor.

(7) FIG. 7 depicts a flow chart of the operating method of the system.

DESCRIPTION OF A PREFERRED EMBODIMENT

(8) The present invention relates to a system and method for online estimate of the filling level of balls (62) and loading level (63) in a rotary mill. FIG. 1 describes an electronic system (100) comprising a set of vibration sensors unit (10), associated with a magnet (20) to transmit data signals via an antenna (17) to a receiver (30) that receives data signals from the antenna (17), an antenna (32), wherein the receiver (30) is connected via optical fiber (35) to a signal processor (40), which in turn communicates to a control server (50) via a UTP cable (48), wherein the control server (50) also obtains data from the mill operation to determine the best filling of balls (62) and load (63). As shown in FIG. 2, the system (100) is installed in the environment of a rotary mill (60), wherein the set of vibration sensors unit (10) comprises at least two vibration sensors (10, 10′) which are placed on the mantle of the mill (60), equidistant at least at an angle greater than 90°, so that the data signal transmitted through the antenna (17) is only received by the antenna (32) of the receiver (30) from only one of the vibration sensors (10, 10′) during the transmission interval; the magnet (20) located on one side and close to the mantle of the mill (60), allows vibration sensors (10, 10′) passing periodically by the magnet (20) to detect the direction and speed of rotation, allowing to determine the angle for wireless transmission to the receiver (30). FIG. 5 details the structure of the set of vibration sensors unit (10), which comprises a pair of magnetic sensors (16) to detect the direction and speed of rotation, providing this information to a first processor (13) as a sync signal, which also receives a signal of the state of charge of a battery (15), which feeds the set of vibration sensors unit (10); a plurality of microphones (11), connected to the first processor (13) receive sounds from the inside of the mill (60) for abnormal noise analysis; a plurality of accelerometers (14) connected to the first processor (13) register the vibrations produced by the load (63) during the grinding process; all information received by the first processor (13) is processed and sent by a transmitter (12) to the receiver (30), located near the mill (60), so as to receive a single data stream only from one of the vibration sensors (10, 101 each time.

(9) As shown in FIG. 6, the receiver (30) sends the information to the signal processor (40) through optical fiber (35), wherein a converter of optical signals to electrical signals (42) sends electrical signals to a second processor (45) that directs them through the communication unit (46) to the control server (50) through the UTP cable (48); data are periodically sent to the control server (50), to which effect they are previously stored in a storage unit (43), when received by the converter of optical signals to electrical ones (42).

(10) FIG. 3 shows a side view of the mill (60), where, for example, two vibration sensors (10, 10′) can be seen on the mantle separated in such a way, that only one of them can transmit to the receiver (30), wherein said transmission is controlled by the first processor (13) which sends a signal to the battery (15) to feed the transmitter (12) only during the transmission interval that each of the vibration sensors (10, 10′) has.

(11) FIG. 4 discloses a sectional view of the mill (60), which shows inside a load (63) and a ball load (62), forming a volume which has a shoulder (66) and a foot (65).

(12) The set of vibration sensor unit (10) processes the information received from the plurality of accelerometers (14) in the first processor (13); the accelerometers (14) have different ranges of operation, so that when there is saturation in any of them, the information is valid in at least one of them, in the understanding that the operating ranges cover the entire spectrum of vibrations produced by the mill (60) during operation.

(13) The first processor (13) collects the information from the accelerometers (14) for a number of turns preset and processes this information covering the entire circumference of the mantle of the mill (60) and sends all values during the interval of time available for each sensor of vibrations (10, 10′); the values obtained allow determining the shoulder (66) and foot (65) of the volume of load in the control server (50).

(14) The data obtained by the accelerometers (14) that are processed by the first processor (13), together with those of sound obtained by microphones (11), and the synchronizing signal for a predetermined amount of turns allows the first processor (13) determining the direction of rotation, the quadrant where the foot (65) should be located and the quadrant where the shoulder (66) should be located. With sound intensity it is verified that the quadrants are the right ones. Then, the average of amplitude and variance of vibrations are calculated for the entire circumference of the mill (60) and for each turn. Then an average between turns is obtained, getting an average and a variance of a turn that represents them all. Subsequently, the line considered with the receiver (30) is awaited and in the transmission time defined before the results obtained are sent along with the possible quadrants for foot (65) and shoulder (66).

(15) The operating method shown in FIG. 7, describes a first stage (71) to obtain the mill operating data (60) and to obtain data from the signal processor (40); wherein the mill operating data (60) correspond to input grain size distribution of fresh ore, tonnage of fresh ore, water supply, rotation speed of the mill (60), refill of balls (62), average power and pressure on the mill (60) bearings, among the most relevant; and wherein the data from the signal processor (40) correspond to the average and variance, which were obtained by a first processor (13).

(16) Step (72) allows the calculation of the instantaneous power p(t) consumed by the mill (60) and determining the foot (65) and shoulder (66) of the load (63) of the mill (60); wherein in order to determine the foot (65), first a first order filter is performed to remove noise, the variance maximum values are sought within the applicable radial quadrant and finally the radial location of most energy is determined, which corresponds to the foot (65) of the total load.

(17) To determine the shoulder (66), first a first order filter is performed to remove noise, the maximum values of reverse variance are sought within the applicable radial quadrant and finally the radial location of most energy is determined, which will correspond to the shoulder (66) of the total load.

(18) Step (73) allows assessing the models of foot (65), shoulder (66), power, pressure, and wear of liners and of balls (62). The models of foot (65) and shoulder (66) correspond to models defined by parametric equations, for example, those described by Morrell, where an angle of foot (65) and shoulder (66) is obtained as a function of loading (63) and balls (62) filling. The model of power available in the state of art and also described by Morrell allows obtaining the power consumed by the mill (60) depending on the filling of loading (63) and balls (62). The model of pressure on the bearings of mill (60) corresponds to linearization of the statistical behavior during the years of operation of the mill (60) where a pressure that depends on the filling of load (63) and balls (62) is obtained. The model of liner wear corresponds to linearization of the statistical behavior during the years of operation of the mill (60) where the actual lining wear during operation is measured and average wear is obtained. The model of balls (62) wear corresponds to linearization of the statistical behavior of consumption of balls (62) over the years considering the sizes of input and output sizes of the balls (62), thereby calculating the wear average.

(19) Step (74) allows iterating the filling values of balls (62) and load (63) within the aforementioned models, and comparing the prediction of models with the values measured by the system and the values obtained from the operation of the mill (60) until achieving a minimum error in the set of variables.

(20) Finally, the step (75) allows obtaining the optimal values for the filling of balls (62) and filling of load (63) for which the overall error is minimal.