JP7579534B2 - Draw slurry concentration control device and method - Google Patents

Description

The present invention relates to an extraction slurry concentration control device and method that stabilizes the concentration of the slurry (sludge) extracted from a thickener device.

Thickener devices have been widely used as sedimentation separation devices that separate suspended solids in industrial wastewater based on differences in specific gravity. The purpose of this thickener device is to obtain a highly concentrated slurry by flocculating and settling the particles contained in the wastewater.

The overall operation of a typical thickener device will now be explained with reference to Figure 6. First, raw water (turbid water) generated during gravel and crushed stone construction and industrial wastewater are collected and mixed with dissolved coagulant 61. Next, the mixed liquid is poured into thickener tank 62 (generally 8 to 20 m in diameter and 4.5 to 6 m in height) installed in thickener device 6.

In the thickener tank 62, the solid particles settle and are separated as the suspended solids (slurry) flow toward the periphery, and the clarified liquid overflows from the top. Meanwhile, the slurry that has settled at the bottom is collected in the center of the bottom by a rotating rake (mud collecting blade) and is removed from the extraction port using a pump 63 or the like. The high-concentration slurry that is extracted is then stored in an intermediate slurry tank 64, and separated into solid and liquid by filtration and dehydration in a filter press device 65, and the filtered water (filtrate) is returned to the thickener tank 62 via a return pipe 66. Meanwhile, the dehydrated cake 67 after filtration is reused or disposed of as waste.

The extraction port for extracting high-concentration slurry from the thickener tank 62 is located in the center of the bottom of the thickener tank 62, and a rake is constantly rotating to collect the settled mud. The thickener device 6 generally has a drive unit (electric motor with a reducer) located in the center as a means for rotating the rake, and the rake attached to the center shaft rotates. The slurry extraction pump is then operated and stopped repeatedly for a set period of time in accordance with the timing of the workers' mud collection work to extract the high-concentration slurry.

It is extremely important for the subsequent solid-liquid separation process that the concentration of the slurry extracted from the bottom of the thickener tank 62 be within a specified range. To determine whether the extracted slurry concentration is within an appropriate range, a method has been known in the past to detect the load on the drive unit electrically using a mechanical device such as a load cell or a current value detector. This is because the concentration of the slurry extracted generally tends to be higher in proportion to the value of the load on the drive unit.

There is also a known method of judging the concentration of the slurry by looking at the motor load current value of the extraction pump 63. Then, for a while after starting the extraction, if the current value of the extraction pump 63 is low, the worker makes the decision to immediately stop the pump operation, but if the current value is high, to continue the extraction for a set period of time. Other known methods include directly detecting the height of the settled and concentrated slurry, and attaching a separate slurry extraction pump for concentration measurement and constantly extracting the slurry.

In the hydrometallurgical process, a thickener that can obtain a concentrated slurry with a high slurry concentration from the bottom of the thickener in a process that includes a thickener, such as a solid-liquid separation process, and a method for managing the thickener have been disclosed (see, for example, Patent Document 1).

Patent No. 6146503

However, there are still problems with the conventional method for detecting the concentration of the extracted slurry. These are described in detail below.

The first problem is that the above method of detecting the load on the rake's drive unit has a tendency not to increase the load for low-fluidity slurry that is under the rake. This causes the problem that the load on the drive unit does not increase even if the slurry settles to the bottom of the thickener tank 62 and becomes very concentrated under the rake.

The second problem is that in the above-mentioned method of simply detecting the load on the extraction pump 63, even if the extraction is stopped temporarily when the slurry is thin, the extraction pump 63 is repeatedly operated and stopped relatively soon afterwards. This often results in a problem of large amounts of thin-concentration slurry being extracted.

As a third problem, if an operator, not wanting thin slurry to be drawn, checks the production status and temporarily stops the operation of the extraction pump 63, there may be cases where the production volume of high-concentration slurry increases during this stoppage period. In this case, the problem occurs that the slurry concentration becomes unnecessarily high because the pump was not operated for a long period of time even though it was necessary to draw it out. If the slurry concentration becomes unnecessarily high, the fluidity of the slurry decreases, and in this case, the current value of the extraction pump 63 becomes low. In other words, if automatic operation is started from this state, even though the slurry concentration is unnecessarily high, it will determine that the concentration of the drawn slurry is low and stop drawing. If these mistakes are repeated, in the worst case scenario, the thickener device may stop and mud may overflow, making it necessary to stop production.

The present invention was made in consideration of the above problems, and aims to provide an extracted slurry concentration control device and method that can stabilize the concentration of the extracted slurry extracted from a thickener tank in a thickener device within an optimal range and reliably obtain a high-concentration slurry.

In order to achieve the above object, the present invention provides an extraction slurry concentration control device that controls the concentration of the slurry extracted from a thickener tank provided in a thickener device, the thickener device comprising: a thickener tank that is a settling tank for performing a settling and separating process of the slurry; a rake that is a mud collecting blade that rotates to collect the slurry that has settled at the bottom of the thickener tank to the center of the bottom of the thickener tank; a drive unit that drives the rotation of the rake; and an extraction pump that extracts the slurry that has settled at the center of the bottom of the thickener tank from an extraction port. The extraction pump comprises an extraction motor, an extraction motor load detection unit that detects the load of the extraction motor, and an extraction motor control unit that controls the extraction motor. The extraction slurry concentration control device comprises: a load information acquisition unit that acquires the load detected by the extraction motor load detection unit, a judgment unit that judges the operation of the extraction pump based on the load acquired by the load information acquisition unit, and a control unit that controls the extraction motor control unit based on the judgment of the judgment unit.

In addition, in the extraction slurry concentration control device, the judgment unit judges that the extraction pump will transition to a long-term standby mode in which the extraction pump will be placed on standby for a predetermined period of time when the load on the extraction motor detected during a certain period of time has fallen below a threshold and this state continues for a predetermined period of time or more, and preferably judges that the extraction pump will perform intermittent operation in which it is repeatedly started and stopped when the load on the extraction motor detected during a certain period of time is equal to or greater than a threshold or the state in which the load is less than the threshold remains for less than the predetermined period of time.

In the extraction slurry concentration control device, the drive unit includes a rake rotation motor for rotating the rake, a rake rotation motor load detection unit for detecting the load on the rake rotation motor, and a rake rotation motor control unit for controlling the rake rotation motor, and it is preferable that the determination unit further permits the extraction pump to be driven when the load detected by the rake rotation motor load detection unit is within a predetermined allowable range.

In addition, in the extraction slurry concentration control device, the judgment unit judges whether the load detected by the rake rotation motor load detection unit is at a first warning level that issues a warning alert or a second warning level that stops the rotation of the rake, and the control unit preferably stops the rake rotation motor so as to stop the operation of the drive unit when it is determined to be at the second warning level.

In order to achieve the above object, the present invention provides a method for controlling the concentration of slurry extracted from a thickener tank provided in a thickener device, the thickener device comprising: a thickener tank which is a settling tank for performing a settling and separating process of the slurry; a rake which is a mud collecting blade that rotates to collect the slurry that has settled at the bottom of the thickener tank to the center of the bottom of the thickener tank; a drive unit which drives the rotation of the rake; and an extraction pump which extracts the slurry that has settled at the center of the bottom of the thickener tank from an extraction port. The extraction pump comprises an extraction motor, an extraction motor load detection unit which detects the load of the extraction motor, and an extraction motor control unit which controls the extraction motor. The extraction slurry concentration control method includes a load information acquisition step which acquires the load detected by the extraction motor load detection unit, a determination step which determines the operation of the extraction pump based on the load acquired in the load information acquisition step, and a control step which controls the extraction motor control unit based on the determination in the determination step.

In addition, in the judgment step of the extraction slurry concentration control method, if the load on the extraction motor detected during a certain period of time is below a threshold and continues to be below a predetermined period of time, it is judged that the extraction pump will transition to a long-term standby mode in which the extraction pump will be placed on standby for a predetermined period of time. On the other hand, if the load on the extraction motor detected during a certain period of time is above a threshold or the load remains below the threshold for less than a predetermined period of time, it is preferable to judge that the extraction pump will perform intermittent operation in which it is repeatedly started and stopped.

In order to achieve the above object, the present invention provides a program for use in an extraction slurry concentration control device that controls the concentration of the slurry extracted from a thickener tank provided in a thickener device, the thickener device comprising: a thickener tank that is a settling tank for performing a settling and separating process of the slurry; a rake that is a mud collecting blade that rotates to collect the slurry that has settled at the bottom of the thickener tank to the center of the bottom of the thickener tank; a drive unit that drives the rotation of the rake; and an extraction pump that extracts the slurry that has settled at the center of the bottom of the thickener tank from an extraction port. The extraction pump comprises an extraction motor, an extraction motor load detection unit that detects the load of the extraction motor, and an extraction motor control unit that controls the extraction motor. The program includes a load information acquisition step that acquires the load detected by the extraction motor load detection unit, a judgment step that judges the operation of the extraction pump based on the load acquired in the load information acquisition step, and a control step that controls the extraction motor control unit based on the judgment in the judgment step.

In addition, in the judgment step of the program, if the load on the extraction motor detected during a certain period of time is below a threshold and continues to be below a predetermined period of time, it is judged that the extraction pump will transition to a long-term standby mode in which the extraction pump will be placed on standby for a predetermined period of time. On the other hand, if the load on the extraction motor detected during a certain period of time is above a threshold or the load remains below the threshold for less than the predetermined period of time, it is preferable to judge that the extraction pump will perform intermittent operation in which it is repeatedly started and stopped.

The extraction slurry concentration control device according to the present invention comprises a load information acquisition unit that acquires the load detected by the extraction motor load detection unit, a judgment unit that judges the operation of the extraction pump based on the load acquired by the load information acquisition unit, and a control unit that controls the extraction motor control unit based on the judgment of the judgment unit. With this configuration, the extraction slurry concentration control device according to the present invention can stabilize the concentration of the extraction slurry extracted from the thickener tank of the thickener device within an optimal range, and reliably obtain a high-concentration slurry.

1A is a partial top view of a thickener device to which an extraction slurry concentration control device according to an embodiment of the present invention is connected, and FIG. 1B is an overall schematic diagram of the same extraction slurry concentration control device. FIG. 2 is a functional block diagram of the extraction slurry concentration control device, the drive unit and the extraction pump provided in the thickener device. FIG. 4 is an explanatory diagram of the determination operation of the determination unit of the above-mentioned extraction slurry concentration control device. 4 is a flowchart showing an operation procedure of the extraction pump of the extraction slurry concentration control device. 4 is a flowchart showing an operation procedure for a drive unit of the above-mentioned extraction slurry concentration control device. FIG. 1 is an explanatory diagram of the overall flow of a conventional thickener device.

(Embodiment)
An extraction slurry concentration control device according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the extraction slurry concentration control device 1 is a device for stably controlling the concentration of a slurry extracted from a thickener device 2, and is connected to a drive unit 3 and an extraction pump 4 via electric wiring or the like. The thickener device 2 is a device for extracting a high-concentration slurry after precipitating and concentrating a slurry (sludge) with a low solid concentration obtained from factory wastewater or the like, and includes a thickener tank 21, a rake 22, the drive unit 3, and the extraction pump 4.

The thickener tank 21 is a settling tank for carrying out a settling and separating process of the slurry. This thickener tank 21 has a cylindrical outer frame 21a and a conical bottom 21b that is inclined toward the center of the bottom. Near the center of this conical bottom 21b, a slurry withdrawal port 21c is provided for discharging and recovering the high-concentration slurry from the thickener tank 21.

The rake 22 is a scraping blade that rotates to collect the slurry that has settled on the bottom 21b of the thickener tank 21 in the center of the bottom of the thickener tank 21. Normally, the rake 22 is arranged along the conical bottom 21b of the tank 21, and is equipped with a rotating shaft 22a and multiple blades 22b attached to the tip of the rotating shaft 22a. As shown by the dotted line in Figure 1, the rake 22 can be adjusted up and down like blades 22b and 22c using the rake up and down means 25 according to the slurry that has settled on the bottom, so that the settled slurry can be stably collected in the center inside the thickener tank 21.

The drive unit 3 drives the rotation of the rake 22. In the thickener device 2, the slurry to be subjected to the sedimentation and concentration process and additives such as a flocculant are first introduced into the tank 23 and mixed, and then the slurry is introduced from the tank 23 into the tank 21 from the center of the top surface of the thickener tank 21 via a gutter 24. The rake 22 installed inside the thickener tank 21 rotates slowly by the drive unit 3 connected to its rotation shaft 22a, ensuring a uniform deposition state. Meanwhile, the overflow liquid that does not contain solids overflows from a groove provided on the upper periphery of the thickener tank 21 and is collected.

As shown in FIG. 2, the drive unit 3 includes a rake rotation motor 3a for rotating the rake 22 (rotating shaft 22a), a rake rotation motor load detection unit 3b, such as a torque indicator, that detects the load on the rake rotation motor 3a, and a rake rotation motor control unit 3c that controls the rake rotation motor 3a.

The extraction pump 4 is a pump device for removing the slurry that has collected in the center of the bottom of the thickener tank 21 from the extraction port 21c. As shown in FIG. 2, the extraction pump 4 includes an extraction motor 4a, an extraction motor load detection unit 4b such as a torque indicator that detects the load on the extraction motor 4a, and an extraction motor control unit 4c that controls the extraction motor 4a.

Next, the functional configuration of the extraction slurry concentration control device 1 will be described with reference to FIG. 2. The extraction slurry concentration control device 1 is actually an ECU (Electronic Control Unit) or a personal computer, which is a control panel, and includes a load information acquisition unit 11, a judgment unit 12, a control unit 13, a transmission/reception unit 14, an input unit 15, and a timer 16.

The load information acquisition unit 11 acquires the load detected by the extraction motor load detection unit 4b and also acquires the load detected by the rake rotation motor load detection unit 3b.

The determination unit 12 determines the operation of the drive unit 3 and the extraction pump 4 based on the load acquired by the load information acquisition unit 11. Specifically, the determination unit 12 determines, for example, based on a predetermined program stored in the memory unit 12a, that the operation of the extraction pump 4 is to be switched to a long-term standby mode in which the extraction pump 4 is placed on standby for a predetermined period of time when the load of the extraction motor 4a detected during a certain period of time has fallen below a threshold value (e.g., 20 A) and this state continues for a predetermined period of time (e.g., 10 seconds) or more. In the long-term standby mode, for example, a timer 16 is used to determine whether or not to resume the operation of the extraction pump 4 after the extraction pump 4 has been stopped for 60 minutes.

On the other hand, when the load of the extraction motor 4a detected during a certain period is equal to or greater than a threshold value (e.g., 20 A) or when the load remains below the threshold value (e.g., 20 A) for less than a predetermined period (e.g., 10 seconds), the determination unit 12 determines that intermittent operation in which the extraction pump 4 is repeatedly operated and stopped is to be performed. The intermittent operation here is, for example, a repeated operation of operating the extraction pump 4 for one minute and stopping the extraction pump 4 for two minutes.

The control unit 13 controls the extraction motor control unit 4c and/or the rake rotation motor control unit 3c based on the judgment of the judgment unit 12. This control is performed by inputting a predetermined control signal from the control unit 13 to the extraction motor control unit 4c and/or the rake rotation motor control unit 3c via the transmission/reception unit 14.

The transmitter/receiver unit 14 receives signals from the extraction pump 4 and/or the drive unit 3 and transmits motor control signals, etc. The input unit 15 is a keyboard or physical switches that an operator uses to control the operation of the drive unit 3 and the extraction pump 4.

Here, an example of the judgment method of the judgment unit 12 will be described with reference to FIG. 3. The judgment unit 12 acquires the value of the extraction motor load detection unit 4b from the load information acquisition unit 11. The first load waveform W1 indicates a case where the load of the extraction motor 4a is equal to or greater than a threshold value (e.g., 20 A). The next waveform W2 indicates a case where the load of the extraction motor 4a remains below the threshold value (e.g., 20 A) for less than a predetermined period (e.g., 10 seconds). In this case, the judgment unit 12 judges to continue the above-mentioned intermittent operation. On the other hand, the waveform W3 indicates a case where the load of the extraction motor 4a remains below the threshold value (e.g., 20 A) for more than a predetermined period (e.g., 10 seconds). In this case, when the load of the extraction motor 4a remains below the threshold value (e.g., 20 A) for more than a predetermined period (e.g., 10 seconds), the operation of the extraction pump 4 is immediately stopped and the operation is switched to a long-term standby mode for a predetermined period (60 minutes).

Next, the operating procedure for the extraction pump 4 of the extraction slurry concentration control device 1 will be described with reference to the flowchart shown in FIG. 4. First, the determination unit 12 detects whether or not there is a trigger for starting operation of the extraction pump 4 from an operator on a control panel or the like (for example, based on a control signal to the extraction motor control unit 4c) (S41). Then, when the determination unit 12 detects a trigger for starting operation (Yes in S41), it refers to the value of the rake rotation motor load detection unit 3b acquired from the load information acquisition unit 11 (S42).

Next, if the detected load is within a predetermined tolerance range (Yes in S42), the determination unit 12 permits and starts the operation of the extraction pump 4 via the control unit 13 (S43). On the other hand, if the detected load is less than the predetermined tolerance (No in S42), the operation of the extraction pump 4 is not started.

Then, while the extraction pump 4 is operating, the determination unit 12 obtains the load value from the extraction pump load detection unit 4b and performs the above control (S44). That is, when the load of the extraction pump 4 detected during a certain period of time is below the threshold and continues to be below the threshold for a predetermined period of time or more (Yes in S44), the determination unit 12 immediately stops the operation of the extraction pump 4 and transitions to a long-term standby mode in which the extraction pump 4 is on standby for a long period of time (S45). On the other hand, when the load of the extraction pump 4 detected during a certain period of time is below the threshold or the state where the load is above the threshold is less than the predetermined period of time (No in S44), the determination unit 12 operates the extraction pump 4 intermittently (S46). Then, the process from S41 onwards is repeated again.

Next, the operation procedure for the drive unit 3 of the extraction slurry concentration control device 1 will be described with reference to the flowchart shown in FIG. 5. In this embodiment, the extraction slurry concentration control device 1 also controls the drive unit 3 in parallel with the control of the extraction pump 4 shown in FIG. 4 above.

First, the determination unit 12 determines whether the load detected by the rake rotation motor load detection unit 3b acquired from the load information acquisition unit 11 is less than a predetermined value (S51). If the load is less than the predetermined value (Yes in S51), the determination unit 12 controls the extraction pump 4 to be deactivated (S52).

On the other hand, if it is equal to or greater than the predetermined value (No in S51), the judgment unit 12 judges whether the load on the drive unit 3 has reached a first warning level that requires a warning (S53). If it is equal to or greater than the first warning level (Yes in S53), a warning alert is issued (S54). At this first warning level, the operator operates the rake 22 to raise it, thereby reducing the load on the drive unit 3, and as a result, the settled slurry can be stably collected in the center of the bottom of the thickener tank 21 without stirring it up and causing it to float again.

Next, it is determined whether the load has reached a second warning level at which rotation of the rake 22 must be stopped (S55). If the load has reached the second warning level (Yes in S55), the control unit 13 controls the operation of the drive unit 3 to stop (S56). On the other hand, if the load on the drive unit 3 has not reached the second warning level (No in S55), the operation of the drive unit 3 continues.

As described above, the thickener device 2 of the extraction slurry concentration control device 1 according to this embodiment includes the thickener tank 21, which is a settling tank for performing a settling and separating process of the slurry, the rake 22, which is a mud collecting blade that rotates to collect the slurry that has settled at the bottom of the thickener tank 21 at the center of the bottom of the thickener tank 21, the drive unit 3 that drives the rotation of the rake 22, and the extraction pump 4 that extracts the slurry that has settled at the center of the bottom of the thickener tank 21 from the extraction port 21c. The extraction pump 4 includes the extraction motor 4a, the extraction motor load detection unit 4b that detects the load of the extraction motor 4a, and the extraction motor control unit 4c that controls the extraction motor 4a. The extraction slurry concentration control device 1 includes a load information acquisition unit 11 that acquires the load detected by the extraction motor load detection unit 4b, a judgment unit 12 that judges the operation of the extraction pump 4 based on the load acquired by the load information acquisition unit 11, and a control unit 13 that controls the extraction motor control unit 4c based on the judgment of the judgment unit 12.

With this configuration, the extraction slurry concentration control device 1 can stabilize the concentration of the extraction slurry extracted from the thickener tank 21 of the thickener device 2 within an optimal range, ensuring the production of a high-concentration slurry. In other words, the extraction slurry concentration control device 1 precisely detects both the load on the drive unit 3 and the current value (load) of the extraction pump 4, and the judgment unit 12 sequentially judges the operation of the drive unit 3 and the extraction motor 4 based on these values.

Specifically, the extraction pump 4 is controlled to operate only when the load value of the drive unit 3 is equal to or greater than a predetermined value, and (1) when the load value of the extraction pump 4 is high, the extraction mode is switched to by repeating the set operation time and standby time in sequence, and (2) when the current value of the extraction pump 4 is low, the standby mode is switched to by not extracting the extraction pump 4 for the set standby time. In parallel with this, the determination unit 12 can determine and set, from the load value of the drive unit 3, a first warning level that issues a caution alert to signal the rake to rise, and a second warning level that stops the pump to prevent damage.

As a result, the extraction slurry concentration control device 1 can extract a stable concentration of slurry by detecting the current value of the extraction pump 4. Also, instead of repeatedly starting and stopping to extract a thin slurry as in the past, a standby mode is created to wait until the concentration becomes high, allowing stable automation regardless of production in the previous process. In parallel with this, the judgment unit 12 also detects the load on the drive unit 3. By detecting the load (torque) on the drive unit 3, the degree of aggregation of the slurry at the bottom of the thickener tank 21 is detected. In other words, it also judges whether the degree of aggregation is at a level at which the extraction process of the slurry can be started, the first warning level when the degree of aggregation of the slurry is about to become very high, or the second warning level (stopped state) at which the degree of aggregation of the slurry may cause damage to the rake blade. This makes it possible to extract a high concentration slurry more stably on the side of the extraction pump 4.

The present invention is not limited to the configuration of the above embodiment, and various modifications are possible within the scope of the invention. For example, the judgment unit 12 of the extraction slurry concentration control device 1 may judge high concentration slurry based only on the load of the extraction pump 4, not necessarily in parallel processing. Also, at the second warning level, not only the drive unit 3 but also the extraction pump 4 may be stopped.

The present invention is not limited to the configuration of the above embodiment, and various modifications are possible within the scope of the invention. In order to achieve the object of the present invention, the present invention can be realized as a method for controlling the concentration of extracted slurry, the steps of which are characteristic constituent means included in an extracted slurry concentration control device, or as a program including these characteristic steps. The program can be stored in a ROM or the like, or can be distributed via a recording medium such as a USB memory or a communication network.

REFERENCE SIGNS LIST 1 Extraction slurry concentration control device 2 Thickener device 3 Drive unit 3a Rake rotation motor 3b Rake rotation motor load detection unit 3c Rake rotation motor control unit 4 Extraction pump 4a Extraction motor 4b Extraction motor load detection unit 4c Extraction motor control unit 11 Load information acquisition unit 12 Determination unit 13 Control unit 14 Transmitting/receiving unit 15 Input unit 16 Timer 21 Thickener tank 21c Extraction port 22 Rake

Claims (8)

A slurry concentration control device for controlling the concentration of a slurry extracted from a thickener tank provided in a thickener device,
The thickener device is
The thickener tank is a settling tank for performing a settling and separating process of the slurry;
A rake which is a rotating mud collecting blade for collecting the slurry deposited at the bottom of the thickener tank at the center of the bottom of the thickener tank;
A drive unit that rotates the rake;
and a withdrawal pump that removes the slurry that has settled at the center of the bottom of the thickener tank from a withdrawal port.
The extraction pump is
A withdrawal motor;
A pull-out motor load detection unit that detects a load of the pull-out motor;
A pull-out motor control unit that controls the pull-out motor,
The extraction slurry concentration control device is
a load information acquisition unit that acquires the load detected by the extraction motor load detection unit;
a determination unit that determines an operation of the withdrawal pump based on the load acquired by the load information acquisition unit;
A control unit that controls the extraction motor control unit based on the determination of the determination unit. The extraction slurry concentration control device according to claim 1, characterized in that the determination unit determines to transition to a long-term standby mode in which the extraction pump is placed on standby for a predetermined period of time when the load on the extraction motor detected during a certain period of time has fallen below a threshold and continues to do so for a predetermined period of time or more, and determines to perform intermittent operation in which the extraction pump is repeatedly started and stopped when the load on the extraction motor detected during a certain period of time is equal to or greater than the threshold or the state in which the load is less than the threshold remains for less than the predetermined period of time. The drive unit is
a rake rotation motor for rotating the rake;
A rake rotation motor load detection unit that detects a load of the rake rotation motor;
A rake rotation motor control unit that controls the rake rotation motor,
3. The device for controlling concentration of slurry extracted according to claim 2, wherein the determination unit further permits operation of the extraction pump when the load detected by the rake rotation motor load detection unit is within a predetermined allowable range. The determination unit determines whether the load detected by the rake rotation motor load detection unit is a first warning level that issues a warning alert or a second warning level that stops the rotation of the rake,
The device for controlling concentration of extracted slurry according to claim 3, characterized in that the control unit controls the motor for rotating the rake to stop operation of the drive unit when the second warning level is reached. A method for controlling the concentration of a slurry extracted from a thickener tank of a thickener device, comprising:
The thickener device is
The thickener tank is a settling tank for performing a settling and separating process of the slurry;
A rake which is a rotating mud collecting blade for collecting the slurry deposited at the bottom of the thickener tank at the center of the bottom of the thickener tank;
A drive unit that rotates the rake;
and a withdrawal pump that removes the slurry that has settled at the center of the bottom of the thickener tank from a withdrawal port.
The extraction pump is
A withdrawal motor;
A pull-out motor load detection unit that detects a load of the pull-out motor;
A pull-out motor control unit that controls the pull-out motor,
The method for controlling the concentration of the extracted slurry comprises:
a load information acquisition step of acquiring a load detected by the extraction motor load detection unit;
a determination step of determining an operation of the withdrawal pump based on the load acquired in the load information acquisition step;
and a control step of controlling the extraction motor control unit based on the determination in the determination step. The extraction slurry concentration control method according to claim 5, characterized in that in the judgment step, if the load on the extraction motor detected during a certain period of time is below a threshold and continues to be below the threshold for a predetermined period of time or more, it is judged that the extraction pump will transition to a long-term standby mode in which the extraction pump is placed on standby for a predetermined period of time, and if the load on the extraction motor detected during a certain period of time is above the threshold or the load remains below the threshold for less than the predetermined period of time, it is judged that the extraction pump will perform intermittent operation in which operation and stopping are repeated. A program for use in an extraction slurry concentration control device that controls the concentration of a slurry extracted from a thickener tank provided in a thickener device,
The thickener device is
The thickener tank is a settling tank for performing a settling and separating process of the slurry;
A rake which is a rotating mud collecting blade for collecting the slurry deposited at the bottom of the thickener tank at the center of the bottom of the thickener tank;
A drive unit that rotates the rake;
and a withdrawal pump that removes the slurry that has settled at the center of the bottom of the thickener tank from a withdrawal port.
The extraction pump is
A withdrawal motor;
A pull-out motor load detection unit that detects a load of the pull-out motor;
A pull-out motor control unit that controls the pull-out motor,
The program is
a load information acquisition step of acquiring a load detected by the extraction motor load detection unit;
a determination step of determining an operation of the withdrawal pump based on the load acquired in the load information acquisition step;
and a control step of controlling the extraction motor control unit based on the determination in the determination step. The program according to claim 7, characterized in that in the determination step, when the load on the extraction motor detected during a certain period of time is below a threshold and continues to be below the threshold for a predetermined period of time or more, it is determined that the extraction pump will transition to a long-term standby mode in which the extraction pump is placed on standby for a predetermined period of time, and when the load on the extraction motor detected during a certain period of time is above the threshold or the load remains below the threshold for less than the predetermined period of time, it is determined that the extraction pump will perform intermittent operation in which operation and stopping are repeated.