Magnetic separator, magnetic separator control device, and magnetic sludge removal method

Abstract

To provide a magnet separator where the reduction of the recovery performance of magnetic sludge and the inconvenience of a device are hardly caused even when the content of the magnetic sludge in a liquid to be treated is increased.SOLUTION: In a magnet separator,: a part of the outer peripheral surface of a magnet drum is immersed in the stream of a liquid to be treated containing magnetic sludge; a removal mechanism removes the magnetic sludge on the outer peripheral surface of the magnet drum from the outer peripheral surface of the magnet drum; a magnetic sludge content information acquisition device acquires magnetic sludge content information on the content of the magnetic sludge contained in the liquid to be treated; and the controlling device varies the removal capacity of the magnetic sludge by the magnet drum in accordance with the magnetic sludge content information acquired by the magnetic sludge content information acquisition device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a magnetic separator, a magnetic separator control device, and a method for removing magnetic sludge.

Background Art

[0002] As a device for removing magnetic sludge from a liquid to be treated containing magnetic sludge, a magnetic separator is known (Patent Document 1, Patent Document 2). In the magnetic separator, a part of a rotating magnetic drum is immersed in the liquid to be treated, and the magnetic sludge in the liquid to be treated is adsorbed on the outer peripheral surface of the magnetic drum by magnetic force. The magnetic sludge adsorbed on the outer peripheral surface is separated from the liquid to be treated as the magnetic drum rotates. After the magnetic sludge adsorbed on the outer peripheral surface of the magnetic drum is separated from the liquid to be treated, it is scraped off from the outer peripheral surface of the magnetic drum by a scraper or the like and discharged to the outside.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the content of magnetic sludge contained in the liquid to be treated increases, there may occur a decrease in the recovery performance of the magnetic sludge and malfunctions of the apparatus due to adsorption of a large amount of magnetic sludge to the magnet drum. An object of the present invention is to provide a magnetic separator in which even when the content of magnetic sludge in the liquid to be treated increases or decreases, a decrease in the recovery performance of the magnetic sludge and malfunctions of the apparatus are less likely to occur. Another object of the present invention relates to a magnetic separator control device for controlling this magnetic separator. Still another object of the present invention is to provide a method for removing magnetic sludge in which even when the content of magnetic sludge in the liquid to be treated increases or decreases, a decrease in the recovery performance of the magnetic sludge and malfunctions of the apparatus are less likely to occur.

Means for Solving the Problems

[0005] According to one aspect of the present invention, a magnet drum that rotates with a part of its outer peripheral surface immersed in the flow of the liquid to be treated containing magnetic sludge and generates a magnetic force on the outer peripheral surface, and a removal mechanism for removing the magnetic sludge on the outer peripheral surface of the magnet drum from the outer peripheral surface of the magnet drum, and in the flow of the liquid to be treated, the content of magnetic sludge contained in the liquid to be treated flowing into the portion where the magnet drum is immersed to measure a magnetic sludge content information acquisition device, and with the magnetic sludge content information acquisition device When the measured content of the magnetic sludge increases, the rotation speed of the magnetic drum is increased to enhance the removal ability of the magnetic sludge. When the content of the magnetic sludge measured by the magnetic sludge content information acquisition device is lower than the reference lower limit value, the rotation of the magnetic drum is stopped, and then the magnetic drum is rotated intermittently. a control device and a magnetic separator is provided.

[0006] According to another aspect of the present invention, A control device for a magnetic separator including a magnetic drum that rotates in a state where a part of the outer peripheral surface is immersed in the flowing liquid to be treated and a magnetic force is generated on the outer peripheral surface. at the location where the magnetic drum is immersed the content of magnetic sludge contained in the flowing-in liquid to be treated to measure When the measured content of the magnetic sludge increases, the rotation speed of the magnetic drum is increased to enhance the removal ability of the magnetic sludge. When the measured content of the magnetic sludge is lower than the reference lower limit value, the rotation of the magnetic drum is stopped, and then the magnetic drum is rotated intermittently. a magnetic separator control device is provided.

[0007] According to still another aspect of the present invention, equipped with a magnetic drum that rotates in a state where a part of the outer peripheral surface is immersed in the flowing liquid to be treated and a magnetic force is generated on the outer peripheral surface Magnetic separator at the location where the magnetic drum is immersed Measure the content of magnetic sludge contained in the incoming liquid to be treated, When the measured content of the magnetic sludge increases, the rotation speed of the magnetic drum is increased to enhance the removal ability of the magnetic sludge. When the measured content of the magnetic sludge is lower than the reference lower limit value, the rotation of the magnetic drum is stopped, and then the magnetic drum is rotated intermittently. A method for removing magnetic sludge is provided.

Advantages of the Invention

[0008] By changing the removal ability of magnetic sludge by the magnetic drum according to the magnetic sludge content information, it is possible to suppress a decrease in the recovery performance of magnetic sludge. When the removal ability is increased as the magnetic sludge content increases, it becomes less likely that the device will malfunction due to the adsorption of a large amount of magnetic sludge to the magnetic drum.

Brief Description of the Drawings

[0009]

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Best Mode for Carrying Out the Invention

[0010] With reference to FIGS. 1 to 3, the magnet separator according to the embodiment will be described. FIG. 1 is a schematic view of the magnet separator according to the embodiment. Inside the housing 10, a flow path 32 through which the liquid to be treated 30 containing the magnetic sludge 31 flows is defined. The housing 10 is provided with an inlet 11 through which the liquid to be treated 30 flows in and an outlet 12 from which the liquid to be treated 30 is discharged. A magnet drum 20 is disposed inside the housing 10. When the liquid to be treated 30 reaches the downstream end of the flow path 32, it is discharged to the outside from the outlet 12.

[0011] The magnet drum 20 is supported inside the housing 10 in a posture such that its central axis is parallel to the liquid surface of the liquid to be treated 30 and orthogonal to the flow direction of the liquid to be treated 30. The magnet drum 20 has an outer cylinder 21 and an inner cylinder 22. A part of the outer peripheral surface of the outer cylinder 21 in the circumferential direction, for example, approximately the lower half circumference, is immersed in the liquid to be treated 30. The outer cylinder 21 rotates about its central axis by a motor 25. The transmission of the driving force from the motor 25 to the outer cylinder 21 is performed by, for example, a sprocket and a chain. The moving direction (circumferential speed direction) of the outer peripheral surface of the outer cylinder 21 is opposite to the flow direction of the liquid to be treated 30.

[0012] The inner cylinder 22 is fixed to the housing 10 and does not rotate, and a plurality of magnets 23 are arranged side by side in the circumferential direction on the outer peripheral surface of the inner cylinder 22. Each of the magnets 23 has magnetic poles with mutually different polarities appearing on the inner peripheral side surface and the outer peripheral side surface, and the S pole and the N pole appear alternately in the circumferential direction. Further, the magnets 23 are arranged in the circumferential direction in a region immersed in the liquid to be treated 30 and in a region from the immersed region to the top portion of the inner cylinder 22 in the circumferential speed direction of the outer peripheral surface of the outer cylinder 21. The plurality of magnets 23 generate a magnetic flux on the outer peripheral surface of the outer cylinder 21. By this magnetic flux, the magnetic sludge 31 is adsorbed to the outer peripheral surface of the outer cylinder 21.

[0013] A part of the bottom surface of the flow path 32 of the liquid to be processed 30 has a shape that reflects the shape of the outer peripheral surface of the outer cylinder 21 such that the radial dimension from the outer peripheral surface of the outer cylinder 21 to the bottom surface of the flow path 32 falls within a predetermined range. When the liquid to be processed 30 flows near the outer peripheral surface of the outer cylinder 21, the magnetic sludge 31 is adsorbed to the outer peripheral surface of the outer cylinder 21 by the magnetic force of the magnet 23. The adsorbed magnetic sludge 31 moves with the rotation of the outer cylinder 21 and is separated from the liquid to be processed 30 by moving above the liquid level of the liquid to be processed 30.

[0014] At a position about 1 / 8 turn advanced in the circumferential velocity direction from the top of the magnet drum 20, the scraper 26 is in contact with the outer peripheral surface of the magnet drum 20. No magnet 23 is arranged at the portion of the outer peripheral surface of the magnet drum 20 where the scraper 26 is in contact. The scraper 26 functions as a removing mechanism for scraping the magnetic sludge 31 on the outer peripheral surface of the magnet drum 20 from the outer peripheral surface. The magnetic sludge 31 scraped by the scraper 26 is collected in the collection container 29 through the discharge path 28.

[0015] At a position from the contact portion between the outer peripheral surface of the magnet drum 20 and the liquid level of the liquid to be processed 30 to the top of the outer peripheral surface in the circumferential velocity direction, the roller 27 is pressed against the outer peripheral surface of the magnet drum 20. The roller 27 rotates in a direction opposite to the rotation direction of the outer cylinder 21 by power being transmitted from the rotation axis of the outer cylinder 21 via a sprocket and a chain. An elastic body is arranged on the outer peripheral surface of the roller 27. When the magnetic sludge 31 adsorbed to the outer peripheral surface of the magnet drum 20 passes between the outer cylinder 21 and the roller 27, the liquid component adhering to the outer peripheral surface of the outer cylinder 21 is removed. Thereby, the magnetic sludge 31 with less liquid component can be separated and collected.

[0016] The pump 40 sends the liquid to be treated 30 containing the magnetic sludge 31 to the inlet 11 of the housing 10. The branch flow path 42 branches off from the main flow path 41 from the pump 40 to the inlet 11 and then merges into the main flow path 41. A detector 43 is inserted into this branch flow path 42. The detector 43 measures the content of the magnetic sludge 31 contained in the liquid to be treated 30 flowing through the branch flow path 42. As the detector 43, for example, a suspended matter concentration meter using a laser can be used. The detector 43 can measure, as the "magnetic sludge content", the weight concentration, volume concentration, number of particles per unit volume, etc. of the magnetic sludge. The content of the magnetic sludge 31 in the liquid to be treated 30 flowing through the main flow path 41 is substantially the same as the content of the magnetic sludge 31 in the liquid to be treated 30 flowing through the branch flow path 42. The detector 43 functions as a "magnetic sludge content information acquisition device" that measures the magnetic sludge content of the liquid to be treated 30.

[0017] The measured value of the content of the magnetic sludge 31 is input to the control device 50. The control device 50 includes a sequencer 51 and an inverter 52. The sequencer 51 controls the inverter 52 so that the magnet drum 20 rotates at a preferable rotational speed according to the measured value of the content of the magnetic sludge 31. The inverter 52 supplies driving power to the motor 25. That is, the control device 50 controls the rotational speed of the magnet drum 20 according to the content of the magnetic sludge 31 contained in the liquid to be treated 30.

[0018] FIG. 2 is a graph showing an example of the relationship between the measured value of the content of the magnetic sludge 31 and the target value of the rotational speed of the magnetic drum 20. The horizontal axis represents the measured value of the content of the magnetic sludge 31, and the vertical axis represents the target value of the rotational speed of the magnetic drum 20. When the measured value of the content of the magnetic sludge 31 falls within the range from the reference lower limit value C1 to the reference upper limit value C3, the control device 50 increases the target value of the rotational speed of the magnetic drum 20 as the measured value of the content of the magnetic sludge 31 increases. For example, the target value of the rotational speed of the magnetic drum 20 is determined so that the thickness of the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 at the position where the roller 27 (FIG. 1) is in contact falls within the target range. The target range of the thickness of the magnetic sludge 31 is, for example, 0.5 mm or more and 1 mm or less.

[0019] When the measured value of the content of the magnetic sludge 31 becomes less than the reference lower limit value C1, the target value of the rotational speed of the magnetic drum 20 is set to zero. That is, when the measured value of the content of the magnetic sludge 31 becomes less than the reference lower limit value C1, the rotation of the magnetic drum 20 is stopped. When the measured value of the content of the magnetic sludge 31 becomes equal to or higher than the rotation start threshold value C2, the rotation of the magnetic drum 20 is restarted. When the measured value of the content of the magnetic sludge 31 exceeds the reference upper limit value C3, the target value of the rotational speed of the magnetic drum 20 is maintained at the rotational speed corresponding to the maximum allowable rotational speed of the motor 25.

[0020] FIG. 3 is a graph showing the time change of the target value of the rotational speed of the magnetic drum 20 during the period when the measured value of the content of the magnetic sludge 31 is below the reference lower limit value C1 (FIG. 2). When the measured value of the content of the magnetic sludge 31 becomes less than the reference lower limit value C1 (FIG. 2) at time t1, the rotation of the magnetic drum 20 is stopped. Thereafter, the control device 50 intermittently rotates the magnetic drum 20 during the period until the measured value of the content of the magnetic sludge 31 becomes equal to or higher than the rotation start threshold value C2. For example, the magnetic drum 20 is rotated at least once every time a certain period T elapses.

[0021] Next, the excellent effects of the embodiments shown in FIGS. 1 to 3 will be described. When the magnetic drum 20 is rotated at a constant speed regardless of the content of the magnetic sludge 31, as the content of the magnetic sludge 31 increases, the amount of the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 increases. When the layer of the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 becomes thick, the magnetic force for adsorbing the magnetic sludge 31 weakens. As a result, the amount of the magnetic sludge 31 that is not adsorbed on the magnetic drum 20 and is discharged from the discharge port 12 increases. That is, the removal ability of the magnetic sludge 31 decreases.

[0022] Also, when the layer of the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 becomes thick, the ability to remove the liquid content by the roller 27 (FIG. 1) becomes insufficient with respect to the amount of the liquid content adhering to the outer peripheral surface of the magnetic drum 20. As a result, a large amount of the liquid content passes through the roller 27 and reaches the scraper 26 (FIG. 1), and a large amount of the liquid content is discharged together with the magnetic sludge 31.

[0023] When the layer of the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 becomes even thicker, an excessive load is applied to the magnetic drum 20 and the roller 27. The excessive load causes a failure in the drive system such as the motor 25.

[0024] In this embodiment, when the content of the magnetic sludge 31 increases, by increasing the rotational speed of the magnetic drum 20, the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 is removed early. As a result, a decrease in the adsorption force due to excessive magnetic sludge 31 being adsorbed on the outer peripheral surface of the magnetic drum 20 is suppressed. For this reason, a decrease in the removal ability of the magnetic sludge 31 can be prevented. Furthermore, excellent effects such as suppression of an increase in the liquid content discharged together with the magnetic sludge 31 and reduction of the risk of failure in the drive system can be obtained.

[0025] Furthermore, when the content of the magnetic sludge 31 becomes less than the reference lower limit value C1 (Figure 2), the rotation of the magnetic drum 20 is stopped, so that the energy consumption can be suppressed. Even when the content of the magnetic sludge 31 is less than the reference lower limit value C1, if a very small amount of magnetic sludge 31 is contained, the magnetic sludge 31 is gradually adsorbed on the outer peripheral surface of the magnetic drum 20, and the layer of the magnetic sludge 31 becomes thick. In this embodiment, even during the period when the content of the magnetic sludge 31 is less than the reference lower limit value C1, the magnetic drum 20 is intermittently rotated, so that it is possible to suppress the layer of the magnetic sludge 31 adsorbed on the outer peripheral surface of the magnetic drum 20 from becoming excessively thick.

[0026] Next, a modified example of the embodiment shown in FIGS. 1 to 3 will be described. In the embodiment shown in FIGS. 1 to 3, in the range where the magnetic sludge content exceeds the reference upper limit value C3 (Figure 2), the target value of the rotation speed of the magnetic drum 20 is constant. For this reason, a state may occur in which the layer of the magnetic sludge adsorbed on the outer peripheral surface of the magnetic drum 20 becomes excessively thick. In this modified example, when the magnetic sludge content exceeds the reference upper limit value C3 (Figure 2), the pressing force of the roller 27 (Figure 1) against the magnetic drum 20 is reduced. Thereby, an excessive increase in the load applied to the motor 25 can be suppressed. Thereby, the risk of failure of the drive system such as the motor 25 can be further reduced.

[0027] Also, in the above embodiment, power is transmitted to the roller 27 (Figure 1) using a sprocket and a chain, and the roller 27 is forcibly rotated. Instead of transmitting power to the roller 27, a configuration may be adopted in which the roller 27 rotates due to the frictional force between the corresponding 21 and the roller 27.

[0028] Next, with reference to FIG. 4, a grinding system according to another embodiment will be described. The grinding system according to this embodiment includes a grinding device and a magnetic separator according to the embodiment shown in FIGS. 1 to 3.

[0029] Figure 4 is a schematic diagram of the grinding system according to this embodiment. The grinding device 60 grinds a workpiece containing a magnetic material with a grinding wheel while supplying a coolant liquid. The coolant liquid containing the magnetic sludge discharged from the grinding device 60 is collected in the coolant tank 61. The pump 40 sucks up the coolant liquid containing the magnetic sludge from the coolant tank 61 and supplies it to the magnetic separator 15. This coolant liquid corresponds to the liquid to be treated supplied to the magnetic separator shown in FIGS. 1 to 3. The coolant liquid from which the magnetic sludge has been removed by the magnetic separator 15 is discharged from the discharge port 12 and returned to the coolant tank 61. The coolant liquid is supplied from the coolant tank 61 to the grinding device 60 and reused.

[0030] Next, the excellent effects of this embodiment will be described. By operating the magnetic separator 15, the magnetic sludge can be removed from the coolant liquid in the coolant tank 61. The coolant liquid from which the magnetic sludge has been removed can be supplied to the grinding device 60. Since the rotational speed of the magnetic drum 20 (FIG. 1) is controlled according to the magnetic sludge content of the coolant liquid sucked up by the pump 40, when the magnetic sludge content of the coolant liquid in the coolant tank 61 increases, the rotational speed of the magnetic drum 20 becomes faster and the magnetic sludge removal ability is enhanced. As a result, the magnetic sludge content of the coolant liquid in the coolant tank 61 can be rapidly reduced.

[0031] Next, with reference to FIG. 5, a grinding system according to still another embodiment will be described. The grinding system according to this embodiment includes a grinding device and a magnetic separator according to the embodiments shown in FIGS. 1 to 3.

[0032] FIG. 5 is a schematic diagram of the grinding system according to this embodiment. The coolant liquid containing magnetic sludge discharged from the grinding device 60 flows into the inlet 11 of the magnetic separator 15 via the pump 40. The coolant liquid discharged from the outlet 12 is collected in the buffer tank 62. The coolant liquid collected in the buffer tank 62 is supplied to the grinding device 60 and reused.

[0033] Next, the excellent effects of this embodiment will be described. Based on the magnetic sludge content of the coolant liquid discharged from the grinding device 60, the magnetic sludge removal ability of the magnetic separator 15 can be increased or decreased. Thereby, sufficient magnetic sludge removal ability can be exhibited, and the coolant liquid with sufficient magnetic sludge removed can be re-supplied to the grinding device 60.

[0034] Next, with reference to FIGS. 6 and 7, the magnetic separator according to still another embodiment will be described. Hereinafter, the description of the configurations common to the embodiments shown in FIGS. 1 to 3 will be omitted.

[0035] FIG. 6 is a schematic diagram of the magnetic separator and the grinding device according to this embodiment. In this embodiment, similar to the embodiment shown in FIG. 4, the coolant liquid discharged from the grinding device 60 is collected in the coolant tank 61, and the coolant liquid in the coolant tank 61 is re-supplied to the grinding device 60. In this embodiment, a flow rate adjustment valve 44 is inserted into the flow path from the discharge port of the pump 40 to the inlet 11 of the magnetic separator 15.

[0036] In the embodiments shown in FIGS. 1 to 3, the rotational speed of the motor 25 is adjusted according to the magnetic sludge content of the coolant liquid. However, in this embodiment, the control device 50 controls the flow rate adjustment valve 44 according to the magnetic sludge content of the coolant liquid, thereby adjusting the flow rate of the coolant liquid flowing into the inlet 11 of the magnetic separator 15.

[0037] FIG. 7 is a graph showing the relationship between the measured value of the magnetic sludge content of the coolant and the target value of the flow rate of the coolant. The horizontal axis represents the measured value of the magnetic sludge content, and the vertical axis represents the target value of the flow rate of the coolant. The control device 50 decreases the target value of the flow rate of the coolant as the measured value of the magnetic sludge content increases. For example, when the measured value of the magnetic sludge content increases from C4 to C5, the control device 50 decreases the target value of the flow rate of the coolant from F2 to F1. Conversely, when the measured value of the magnetic sludge content decreases from C5 to C4, the control device 50 increases the target value of the flow rate of the coolant from F1 to F2. When the measured value of the magnetic sludge content exceeds the allowable upper limit value C6, the control device 50 sets the target value of the flow rate of the coolant to zero. That is, the pump 40 is stopped.

[0038] Next, the excellent effects of this embodiment will be described. When the magnetic sludge content of the coolant becomes excessive, as described in the embodiments shown in FIGS. 1 to 3, a large amount of liquid is recovered together with the magnetic sludge, or the risk of failure of the drive system such as the motor 25 increases. In this embodiment, when the magnetic sludge content becomes excessively large, the flow rate of the coolant is decreased. Decreasing the flow rate of the coolant corresponds to decreasing the magnetic sludge removal ability of the magnetic separator 15. Therefore, it is possible to suppress the layer of magnetic sludge adsorbed on the outer peripheral surface of the magnetic drum 20 from becoming excessively thick. As a result, it is possible to suppress a large amount of liquid from being discharged together with the magnetic sludge and reduce the risk of failure of the drive system such as the motor 25.

[0039] Next, with reference to FIGS. 8 and 9, a magnetic separator according to still another embodiment will be described. Hereinafter, the description of the configurations common to the embodiments shown in FIGS. 1 to 3 will be omitted.

[0040] FIG. 8 is a schematic diagram of the magnetic separator and the grinding apparatus according to the present embodiment. In the present embodiment, similar to the embodiment shown in FIG. 5, the coolant liquid discharged from the grinding apparatus 60 flows into the inlet 11 of the magnetic separator 15 through the pump 40. In the embodiments shown in FIGS. 1 to 3, the measured value of the magnetic sludge content of the liquid to be processed detected by the detector 43 is input to the control device 50. On the other hand, in the present embodiment, the grinding conditions of the grinding apparatus 60 are input from the output unit 45 of the grinding apparatus 60 to the control device 50. The grinding conditions include, for example, the depth of cut of the grinding wheel into the workpiece, the moving speed of the workpiece, and the like. Since the generation amount of magnetic sludge depends on these grinding conditions, these grinding conditions can be referred to as magnetic sludge content information related to the magnetic sludge content of the coolant liquid. Further, the output unit 45 has a function as a magnetic sludge content information acquisition unit.

[0041] The control device 50 determines the target value of the rotational speed of the magnetic drum 20 according to the grinding conditions of the grinding apparatus 60.

[0042] FIG. 9 is a graph showing an example of the relationship between the grinding conditions and the target value of the rotational speed of the magnetic drum 20. The horizontal axis represents the product of the depth of cut of the grinding wheel and the moving speed of the workpiece, and the vertical axis represents the target value of the rotational speed of the magnetic drum 20. As the depth of cut of the grinding wheel increases, the generation amount of magnetic sludge increases, and as the moving speed of the workpiece increases, the generation amount of magnetic sludge per unit time increases. That is, an increase in the product of the depth of cut of the grinding wheel and the moving speed of the workpiece means an increase in the magnetic sludge content of the coolant liquid.

[0043] When the product of the depth of cut of the grinding wheel and the moving speed of the workpiece is within a range not exceeding the reference upper limit value G1, the control device 50 sets the target value of the rotational speed of the magnetic drum 20 to R1. When the product of the depth of cut of the grinding wheel and the moving speed of the workpiece exceeds the reference upper limit value G1, the target value of the rotational speed of the magnetic drum 20 is increased from R1 to R2. When the product of the depth of cut of the grinding wheel and the moving speed of the workpiece is zero, that is, when grinding is not being performed, the rotation of the magnetic drum 20 is stopped by setting the target value of the rotational speed of the magnetic drum 20 to zero.

[0044] Next, the excellent effects of this embodiment will be described. Also in this embodiment, similar to the embodiments shown in FIGS. 1 to 3, excellent effects such as prevention of deterioration of the magnetic sludge recovery performance, suppression of an increase in the liquid component discharged together with the magnetic sludge, and reduction of the risk of failure of the drive system can be obtained.

[0045] In the above embodiment, a drum-type magnetic separator having a magnet drum was exemplified. However, the technical idea of changing the magnetic sludge removal ability according to the content of the magnetic sludge can also be applied to magnetic separators of other structures, for example, a conveyor-type magnetic separator.

[0046] It goes without saying that each of the above-described embodiments is an exemplification, and partial substitution or combination of the configurations shown in different embodiments is possible. Regarding the same operational effects due to the same configurations of a plurality of embodiments, they will not be sequentially mentioned for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

Explanation of Reference Numerals

[0047] 10 Housing 11 Inlet 12 Outlet 15 Magnetic Separator 20 Magnet Drum 21 Outer Cylinder 22 Inner Cylinder 23 Magnet 25 Motor 26 Scraper 27 Roller 28 Discharge Path 29 Recovery Container 30 Liquid to be Treated 31 Magnetic Sludge 32 Flow Path of Liquid to be Treated 40 Pump 41 Main Flow Path 42 Branch Flow Path 43 Detector 44 Flow rate adjustment valve 45 Output section 50 Control device 51 Sequencer 52 Inverter 60 Grinding device 61 Coolant tank 62 Buffer tank

Claims

1. A magnetic separator comprising: a magnet drum, a part of the outer peripheral surface of which is immersed in a flow of a liquid to be treated containing magnetic sludge, and which rotates in a state where a magnetic force is generated on the outer peripheral surface; a removing mechanism for removing the magnetic sludge on the outer peripheral surface of the magnet drum from the outer peripheral surface of the magnet drum; a magnetic sludge content information acquisition device for measuring the content of magnetic sludge contained in the liquid to be treated flowing into a location where the magnet drum is immersed in the flow of the liquid to be treated; a control device that, when the content of magnetic sludge measured by the magnetic sludge content information acquisition device increases, increases the rotational speed of the magnet drum to enhance the removal ability of the magnetic sludge, and when the content of magnetic sludge measured by the magnetic sludge content information acquisition device falls below a reference lower limit value, stops the rotation of the magnet drum and then intermittently rotates the magnet drum.

2. Furthermore, the magnetic separator according to claim 1, further comprising a roller that is pressed against the outer peripheral surface of the magnet drum and rotates in a direction opposite to the rotation direction of the magnet drum, wherein the roller is pressed against the outer peripheral surface of the magnet drum between a location immersed in the liquid to be treated and a location where the magnetic sludge is removed by the removing mechanism.

3. A control device for a magnetic separator including a magnet drum, a part of the outer peripheral surface of which is immersed in a flow of a liquid to be treated flowing in and which rotates in a state where a magnetic force is generated on the outer peripheral surface, the control device comprising: measuring the content of magnetic sludge contained in the liquid to be treated flowing into a location where the magnet drum is immersed; when the measured content of magnetic sludge increases, increasing the rotational speed of the magnet drum to enhance the removal ability of the magnetic sludge, and when the measured content of magnetic sludge falls below a reference lower limit value, stopping the rotation of the magnet drum and then intermittently rotating the magnet drum.

4. Measuring the content of magnetic sludge contained in the liquid to be treated flowing into a location where a magnet drum provided in a magnetic separator, a part of the outer peripheral surface of which is immersed in a flow of the liquid to be treated and which rotates in a state where a magnetic force is generated on the outer peripheral surface, is immersed. ​ When the measured content of the magnetic sludge increases, the rotation speed of the magnetic drum is increased to enhance the removal ability of the magnetic sludge. When the measured content of the magnetic sludge falls below the reference lower limit value, the rotation of the magnetic drum is stopped, and then the magnetic drum is intermittently rotated. A method for removing magnetic sludge.

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