Coal Slime Flotation Automatic Control System

Abstract

The present invention relates to the field of coal mine automation technology, and proposes an automatic control system for coal slime flotation, including a flotation machine, and also including a clean coal ash automatic detection circuit, a slurry flow detection circuit, a slurry concentration detection circuit and a flow regulation circuit all connected to a main control chip, wherein the slurry flow detection circuit is used to detect the slurry flow injected into the flotation machine, the slurry concentration detection circuit is used to detect the slurry concentration injected into the flotation machine, the flow regulation circuit is used to adjust the dosage of a frother and a collector, and the clean coal ash automatic detection circuit includes a laser diode LD1, a photodiode D1, a switch tube Q2, a resistor R5, a resistor R1, a resistor R2 and a switch tube Q3, wherein the anode of the laser diode LD1 is connected to a power supply VCC, the cathode of the laser diode LD1 is connected to a first end of the switch tube Q2, and the second end of the switch tube Q2 is grounded through a resistor R5. Through the above technical scheme, the problem of low control accuracy of clean coal ash in the coal slime flotation system in the related art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine automation, and in particular to an automatic control system for coal slime flotation. Background Art

[0002] The coal sludge flotation process is based on the different surface properties of minerals, that is, the different effects of clean coal and gangue on water, bubbles, and reagents in water. The hydrophobic coal particles adhere to the bubbles, and the hydrophilic gangue particles are retained in the coal slurry, thereby achieving the separation of clean coal and gangue. Clean coal ash content (ash content refers to the non-combustible material remaining after burning under specified conditions) is an important indicator of the flotation process. By adjusting the amount of reagents and the process parameters of the flotation machine according to the size of the clean coal ash content, a clean coal product with qualified ash content can be achieved. At present, the commonly used online detection methods for clean coal ash content mainly include X-ray detection method, laser induced breakdown spectroscopy analysis method and image recognition method. The detection accuracy of these methods needs to be improved, resulting in the inability to accurately control the clean coal ash content. Summary of the invention

[0003] The invention provides an automatic control system for coal slime flotation, which solves the problem of low control precision of clean coal ash content in the coal slime flotation system in the related art.

[0004] The technical scheme of the present invention is as follows: it includes a flotation machine, and also includes a clean coal ash automatic detection circuit, a slurry flow detection circuit, a slurry concentration detection circuit and a flow regulation circuit all connected to a main control chip, the slurry flow detection circuit is used to detect the slurry flow injected into the flotation machine, the slurry concentration detection circuit is used to detect the slurry concentration injected into the flotation machine, the flow regulation circuit is used to adjust the amount of frother and collector, the clean coal ash automatic detection circuit includes a laser diode LD1, a photodiode D1, a switch tube Q2, a resistor R5, a resistor R1, a resistor R2 and a switch tube Q3,

[0005] The anode of the laser diode LD1 is connected to the power supply VCC, the cathode of the laser diode LD1 is connected to the first end of the switch tube Q2, the second end of the switch tube Q2 is grounded through a resistor R5, the photodiode D1 is used to receive the laser emitted by the laser diode LD1, the cathode of the photodiode D1 is connected to the power supply VCC, and the anode of the photodiode D1 is grounded through a resistor R1.

[0006] The anode of the diode D1 is connected to the control end of the switch tube Q3, the first end of the switch tube Q3 is connected to the second end of the resistor R2, the first end of the resistor R2 is connected to the power supply VCC, the first end of the switch tube Q3 is connected to the control end of the switch tube Q2, and the second end of the switch tube Q3 is grounded.

[0007] Furthermore, it also includes a capacitor C1, a first end of the capacitor C1 is connected to a power source VCC via a resistor R2, and a second end of the capacitor C1 is grounded.

[0008] Furthermore, the first end of the resistor R2, the anode of the laser diode LD1 and the cathode of the photodiode D1 are connected at one point, the anode of the laser diode LD1 and the power supply VCC are connected via a switch tube Q1, and a comparator U2 and an OR gate U1 are also included.

[0009] The non-inverting input terminal of the comparator U2 is connected to the anode of the diode D1, the inverting input terminal of the comparator U2 is connected to the reference voltage VREF, the output terminal of the comparator U2 is connected to the first input terminal of the OR gate U1, the second input terminal of the OR gate U1 is connected to the first output terminal of the main control chip, the output terminal of the OR gate U1 is connected to the control terminal of the switch tube Q1, the first terminal of the switch tube Q1 is connected to the power supply VCC, and the second terminal of the switch tube Q1 is connected to the anode of the laser diode LD1.

[0010] Furthermore, it includes a resistor R6 and a resistor R7, wherein the first end of the resistor R6 is connected to the power supply 5V, the second end of the resistor R6 is grounded through the resistor R7, and the second end of the resistor R6 is used as the reference voltage VREF and connected to the inverting input end of the comparator U2.

[0011] Furthermore, the flow regulation circuit includes a DAC chip U6 and two drive circuits with the same circuit structure, wherein one drive circuit includes an operational amplifier U8B, a resistor R24, a resistor R23, a switch tube Q5 and a resistor R20.

[0012] The clock end, data input end and data output end of the DAC chip U6 are all connected to the main control chip, the reference voltage input end of the DAC chip U6 is connected to the reference voltage Ref, the first analog output end of the DAC chip U6 is connected to the first end of the resistor R24, the second end of the resistor R24 ​​is grounded through the resistor R23, the second end of the resistor R24 ​​is connected to the in-phase input end of the operational amplifier U8B, the inverting input end of the operational amplifier U8B is grounded, the output end of the operational amplifier U8B is connected to the control end of the switch tube Q5, the first end of the switch tube Q5 is connected to the power supply 12V, the second end of the switch tube Q5 is used to connect to the first end of the first electric regulating valve coil, the first end of the resistor R20 is used to be connected to the second end of the first electric regulating valve coil, and the second end of the resistor R20 is grounded.

[0013] Furthermore, it also includes a reference voltage chip U7, the power supply end of the reference voltage chip U7 is connected to the power supply 5V, and the output end of the reference voltage chip U7 is used as the reference voltage Ref and connected to the reference voltage input end of the DAC chip U6.

[0014] Furthermore, the slurry flow detection circuit includes a slurry flow meter and a slurry flow meter power supply circuit. The slurry flow meter is used to detect the slurry flow. The output of the slurry flow meter is connected to the main control chip.

[0015] The slurry flowmeter power supply circuit includes an operational amplifier U4A and an operational amplifier U4B connected in sequence, the inverting input terminal of the operational amplifier U4A is connected to the third output terminal of the DAC chip U6 through a resistor R16, the output terminal of the operational amplifier U4A is feedback-connected to the inverting input terminal of the operational amplifier U4A through a resistor R11, the non-inverting input terminal of the operational amplifier U4A is grounded, the output terminal of the operational amplifier U4A is connected to the inverting input terminal of the operational amplifier U4B through a resistor R10, the output terminal of the operational amplifier U4B is feedback-connected to the inverting input terminal of the operational amplifier U4B through a resistor R9, the non-inverting input terminal of the operational amplifier U4B is grounded, and the output terminal of the operational amplifier U4B serves as the output of the slurry flowmeter power supply circuit and is connected to the power supply terminal of the slurry flowmeter.

[0016] Furthermore, the slurry concentration detection circuit includes an ultrasonic concentration detector, a resistor R13 and an operational amplifier U5 connected in sequence, the ultrasonic concentration detector is used to detect the slurry concentration, the first end of the resistor R13 is connected to the output end of the ultrasonic concentration detector, the second end of the resistor R13 is grounded, the first end of the resistor R13 is connected to the inverting input end of the operational amplifier U5, the non-inverting input end of the operational amplifier U5 is grounded, the output end of the operational amplifier U5 is feedback connected to the inverting input end of the operational amplifier U5, and the output end of the operational amplifier U5 is used as the output of the slurry concentration detection circuit and is connected to the main control chip.

[0017] The working principle and beneficial effects of the present invention are:

[0018] Laser induced breakdown spectroscopy uses high-energy pulsed laser to irradiate the coal surface, causing the coal in the area to form plasma, and various elements in the plasma emit light. By measuring the spectrum, the content information of each element can be obtained. On the basis of the existing laser induced breakdown spectroscopy, the present invention improves the control of the laser emission circuit to achieve the stability of the emitted laser power, thereby ensuring the stability of the spectrum intensity, and ultimately improving the detection accuracy of clean coal ash. According to the real-time detection results of clean coal ash, slurry flow rate and slurry concentration, the dosage of frother and collector is adjusted, which is beneficial to improve the control accuracy of clean coal ash and improve the clean coal yield.

[0019] Specifically, the present invention uses NPN transistors as switch tubes Q3 and Q2. When the power of the laser diode LD1 increases, the current of the photodiode D1 increases, the voltage division of the resistor R1 increases, the base potential of the switch tube Q3 increases, the collector current of the switch tube Q3 increases, the voltage division of the resistor R2 increases, the base potential of the switch tube Q2 decreases, the collector current of the switch tube Q2 decreases, and the power of the laser diode LD1 decreases; conversely, when the power of the laser diode LD1 decreases, the current of the photodiode D1 decreases, the voltage division of the resistor R1 decreases, the base potential of the switch tube Q3 decreases, the collector current of the switch tube Q3 decreases, the voltage division of the resistor R2 decreases, the base potential of the switch tube Q2 increases, the collector current of the switch tube Q2 increases, and the power of the laser diode LD1 increases. Through the above adjustment process, stable control of the power of the laser diode LD1 is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a schematic diagram of a clean coal ash content automatic detection circuit in the present invention;

[0022] Figure 2 It is the principle diagram of the flow regulation circuit in the present invention;

[0023] Figure 3 This is a schematic diagram of a slurry flow detection circuit in the present invention;

[0024] Figure 4 This is a schematic diagram of a slurry concentration detection circuit in the present invention;

[0025] In the figure: 1 clean coal ash automatic detection circuit, 2 flow regulation circuit, 3 slurry flow detection circuit, 4 slurry concentration detection circuit. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The coal slime flotation automatic control system of this embodiment includes a flotation machine, and also includes a clean coal ash automatic detection circuit, a slurry flow detection circuit, a slurry concentration detection circuit and a flow regulation circuit, all of which are connected to the main control chip. The slurry flow detection circuit is used to detect the slurry flow injected into the flotation machine, the slurry concentration detection circuit is used to detect the slurry concentration injected into the flotation machine, and the flow regulation circuit is used to adjust the dosage of the frother and the collector, such as Figure 1As shown, the clean coal ash content automatic detection circuit includes a laser diode LD1, a photodiode D1, a switch tube Q2, a resistor R5, a resistor R1, a resistor R2 and a switch tube Q3.

[0028] The anode of the laser diode LD1 is connected to the power supply VCC, the cathode of the laser diode LD1 is connected to the first end of the switch tube Q2, the second end of the switch tube Q2 is grounded through the resistor R5, the photodiode D1 is used to receive the laser emitted by the laser diode LD1, the cathode of the photodiode D1 is connected to the power supply VCC, and the anode of the photodiode D1 is grounded through the resistor R1.

[0029] The anode of the diode D1 is connected to the control end of the switch tube Q3, the first end of the switch tube Q3 is connected to the second end of the resistor R2, the first end of the resistor R2 is connected to the power supply VCC, the first end of the switch tube Q3 is connected to the control end of the switch tube Q2, and the second end of the switch tube Q3 is grounded.

[0030] Laser induced breakdown spectroscopy uses high-energy pulsed laser to irradiate the coal surface, causing the coal in the area to form plasma. Various elements in the plasma emit light, and the content information of each element can be obtained by measuring the spectrum. Based on the existing laser induced breakdown spectroscopy, this embodiment improves the control of the laser emission circuit to achieve the stability of the emitted laser power, thereby ensuring the stability of the spectrum intensity, and ultimately improving the detection accuracy of clean coal ash. According to the real-time detection results of clean coal ash, slurry flow rate and slurry concentration, the dosage of frother and collector is adjusted, which is conducive to improving the control accuracy of clean coal ash and improving the clean coal yield.

[0031] Specifically, this embodiment uses NPN transistors as switch tubes Q3 and Q2. When the power of the laser diode LD1 increases, the current of the photodiode D1 increases, the voltage division of the resistor R1 increases, the base potential of the switch tube Q3 increases, the collector current of the switch tube Q3 increases, the voltage division of the resistor R2 increases, the base potential of the switch tube Q2 decreases, the collector current of the switch tube Q2 decreases, and the power of the laser diode LD1 decreases; conversely, when the power of the laser diode LD1 decreases, the current of the photodiode D1 decreases, the voltage division of the resistor R1 decreases, the base potential of the switch tube Q3 decreases, the collector current of the switch tube Q3 decreases, the voltage division of the resistor R2 decreases, the base potential of the switch tube Q2 increases, the collector current of the switch tube Q2 increases, and the power of the laser diode LD1 increases. Through the above adjustment process, stable control of the power of the laser diode LD1 is achieved.

[0032] Further, if Figure 1 As shown, a capacitor C1 is also included, a first end of the capacitor C1 is connected to a power source VCC through a resistor R2, and a second end of the capacitor C1 is grounded.

[0033] The capacitor C1 is connected in parallel between the base of the switch tube Q2 and the ground to prevent the base potential of the switch tube Q2 from suddenly increasing, causing the current of the laser diode LD1 to suddenly increase, thereby preventing the sudden increase in current from damaging the laser diode LD1.

[0034] Further, if Figure 1 As shown, the first end of the resistor R2, the anode of the laser diode LD1 and the cathode of the photodiode D1 are connected at one point, the anode of the laser diode LD1 and the power supply VCC are connected through the switch tube Q1, and also includes a comparator U2 and an OR gate U1.

[0035] The non-inverting input terminal of the comparator U2 is connected to the anode of the diode D1, the inverting input terminal of the comparator U2 is connected to the reference voltage VREF, the output terminal of the comparator U2 is connected to the first input terminal of the OR gate U1, the second input terminal of the OR gate U1 is connected to the first output terminal of the main control chip, the output terminal of the OR gate U1 is connected to the control terminal of the switch tube Q1, the first terminal of the switch tube Q1 is connected to the power supply VCC, and the second terminal of the switch tube Q1 is connected to the anode of the laser diode LD1.

[0036] The main control chip can realize the switching control of the laser diode LD1 by controlling the on and off of the switch tube Q1; at the same time, when the power of the laser diode LD1 exceeds the set value, the current of the photodiode D1 is too large, the voltage division of the resistor R1 increases, and the voltage at the non-inverting input terminal of the comparator U2 is greater than the reference voltage VREF. The comparator U2 outputs a high-level signal to the first input terminal of the OR gate U1, and the OR gate U1 outputs a high level to the control terminal of the switch tube Q1. The switch tube Q1 is turned off, and the power supply of the laser diode LD1 is turned off in time to avoid damage to the laser diode LD1.

[0037] Further, if Figure 1 As shown, it also includes a resistor R6 and a resistor R7. The first end of the resistor R6 is connected to the power supply 5V, and the second end of the resistor R6 is grounded through the resistor R7. The second end of the resistor R6 is used as a reference voltage VREF and is connected to the inverting input end of the comparator U2.

[0038] Resistors R6 and R7 form a voltage divider circuit, which is connected in series between the power supply 5V and the ground. The divided voltage of resistor R7 is used as the reference voltage VREF. According to actual needs, the size of the reference voltage VREF can be adjusted by the resistance values ​​of resistors R6 and R7. The circuit structure is simple and easy to operate.

[0039] Further, if Figure 2 As shown, the flow regulation circuit includes a DAC chip U6 and two drive circuits with the same circuit structure, wherein one drive circuit includes an operational amplifier U8B, a resistor R24, a resistor R23, a switch tube Q5 and a resistor R20.

[0040] The clock end, data input end and data output end of the DAC chip U6 are all connected to the main control chip, the reference voltage input end of the DAC chip U6 is connected to the reference voltage Ref, the first analog output end of the DAC chip U6 is connected to the first end of the resistor R24, the second end of the resistor R24 ​​is grounded through the resistor R23, the second end of the resistor R24 ​​is connected to the in-phase input end of the operational amplifier U8B, the inverting input end of the operational amplifier U8B is grounded, the output end of the operational amplifier U8B is connected to the control end of the switch tube Q5, the first end of the switch tube Q5 is connected to the power supply 12V, the second end of the switch tube Q5 is used to connect to the first end of the first electric control valve coil, the first end of the resistor R20 is used to be connected to the second end of the first electric control valve coil, and the second end of the resistor R20 is grounded.

[0041] In this embodiment, the first electric regulating valve is arranged on the dosing pipeline of the foaming agent, and the second electric regulating valve is arranged on the dosing pipeline of the collector. The two driving circuits are used to drive the first electric regulating valve and the second electric regulating valve respectively. Taking the driving circuit of the first electric regulating valve as an example, the main control chip outputs different digital quantities to the data input end of the DAC chip U6, and the first analog output end of the DAC chip U6 outputs the corresponding analog voltage DAC1 to the in-phase input end of the operational amplifier U8B. According to the "virtual disconnection" characteristic of the operational amplifier, the current flowing through the coil of the first electric regulating valve is equal to the current flowing through the resistor R23, specifically:

[0042] I1=ui1 / R23 (1)

[0043] Due to the voltage divider effect of resistors R24 and R23, we get:

[0044] ui1= R23×DAC1 / (R23+R24) (2)

[0045] According to formula (1) and formula (2), it can be obtained that the current flowing through the coil of the first electric control valve is proportional to the analog voltage DAC1. Therefore, according to actual needs, the current flowing through the coil of the first electric control valve can be adjusted by outputting different digital quantities to the DAC chip U6 through the main control chip, thereby adjusting the opening of the first electric control valve and realizing the regulation of the foaming agent flow.

[0046] Similarly, the main control chip outputs different digital quantities to the data input end of the DAC chip U6, and the second analog output end of the DAC chip U6 outputs the corresponding analog voltage DAC2 to the in-phase input end of the operational amplifier U8C, which can adjust the current flowing through the coil of the second electric control valve, thereby adjusting the opening of the second electric control valve and realizing the regulation of the collector flow rate.

[0047] In this embodiment, the arrangement of the DAC chip U6, the operational amplifier U8B, and the operational amplifier U8C realizes multi-channel regulation of the frother flow rate and the collector flow rate, and has a simple circuit structure and convenient control.

[0048] Further, if Figure 2 As shown, it also includes a reference voltage chip U7, the power supply end of the reference voltage chip U7 is connected to the power supply 5V, and the output end of the reference voltage chip U7 is used as a reference voltage Ref and connected to the reference voltage input end of the DAC chip U6.

[0049] The reference voltage chip U7 provides a reliable reference voltage for the DAC chip U6, which is beneficial to the reliable operation of the DAC chip U6.

[0050] Furthermore, the slurry flow detection circuit includes a slurry flow meter and a slurry flow meter power supply circuit. The slurry flow meter is used to detect the slurry flow. The output of the slurry flow meter is connected to the main control chip.

[0051] like Figure 3 As shown, the power supply circuit of the slurry flowmeter includes an operational amplifier U4A and an operational amplifier U4B connected in sequence, the inverting input terminal of the operational amplifier U4A is connected to the third output terminal of the DAC chip U6 through a resistor R16, the output terminal of the operational amplifier U4A is feedback-connected to the inverting input terminal of the operational amplifier U4A through a resistor R11, the non-inverting input terminal of the operational amplifier U4A is grounded, the output terminal of the operational amplifier U4A is connected to the inverting input terminal of the operational amplifier U4B through a resistor R10, the output terminal of the operational amplifier U4B is feedback-connected to the inverting input terminal of the operational amplifier U4B through a resistor R9, the non-inverting input terminal of the operational amplifier U4B is grounded, and the output terminal of the operational amplifier U4B serves as the output of the power supply circuit of the slurry flowmeter and is connected to the power supply terminal of the slurry flowmeter.

[0052] In this embodiment, the slurry flowmeter specifically adopts an electromagnetic flowmeter. In order to meet the different requirements of various types of electromagnetic flowmeters for excitation voltage, this embodiment is provided with a slurry flowmeter power supply circuit with adjustable output voltage. Its working principle is as follows: the main control chip outputs different digital quantities to the DAC chip U6, and the third analog output terminal of the DAC chip U6 outputs the corresponding analog voltage DAC3 to the inverting input terminal of the operational amplifier U4A. The operational amplifier U4A and the operational amplifier U4B constitute a two-stage inverting proportional amplifier circuit to amplify the analog voltage DAC3 as the power supply of the slurry flowmeter. According to actual needs, the output voltage of the slurry flowmeter power supply circuit can be adjusted by adjusting the ratio of the resistor R11 and the resistor R16, and the ratio of the resistor R9 and the resistor R10.

[0053] Further, if Figure 4As shown, the slurry concentration detection circuit includes an ultrasonic concentration detector, a resistor R13 and an operational amplifier U5 connected in sequence. The ultrasonic concentration detector is used to detect the slurry concentration. The first end of the resistor R13 is connected to the output end of the ultrasonic concentration detector, the second end of the resistor R13 is grounded, the first end of the resistor R13 is connected to the inverting input end of the operational amplifier U5, the non-inverting input end of the operational amplifier U5 is grounded, the output end of the operational amplifier U5 is feedback connected to the inverting input end of the operational amplifier U5, and the output end of the operational amplifier U5 is used as the output of the slurry concentration detection circuit and is connected to the main control chip.

[0054] In this embodiment, the slurry concentration is detected by an ultrasonic concentration detector. The current signal output by the ultrasonic concentration detector is connected to the circuit through terminal H1 and converted into a voltage signal through resistor R13; the operational amplifier U5 constitutes a voltage follower to play the role of impedance matching, and the terminal voltage of resistor R13 is input into the AD channel of the main control chip through the operational amplifier U5, so that the main control chip can accurately read the output data of the ultrasonic concentration detector.

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A coal slime flotation automatic control system, comprising a flotation machine, and also comprising a clean coal ash automatic detection circuit (1), a slurry flow detection circuit (3), a slurry concentration detection circuit (4) and a flow regulation circuit (2) all connected to a main control chip, wherein the slurry flow detection circuit (3) is used to detect the slurry flow injected into the flotation machine, the slurry concentration detection circuit (4) is used to detect the slurry concentration injected into the flotation machine, and the flow regulation circuit (2) is used to adjust the dosage of a frother and a collector, characterized in that: The clean coal ash content automatic detection circuit (1) comprises a laser diode LD1, a photodiode D1, a switch tube Q2, a resistor R5, a resistor R1, a resistor R2 and a switch tube Q3. The anode of the laser diode LD1 is connected to the power supply VCC, the cathode of the laser diode LD1 is connected to the first end of the switch tube Q2, the second end of the switch tube Q2 is grounded through a resistor R5, the photodiode D1 is used to receive the laser emitted by the laser diode LD1, the cathode of the photodiode D1 is connected to the power supply VCC, and the anode of the photodiode D1 is grounded through a resistor R1. The anode of the photodiode D1 is connected to the control end of the switch tube Q3, the first end of the switch tube Q3 is connected to the second end of the resistor R2, the first end of the resistor R2 is connected to the power supply VCC, the first end of the switch tube Q3 is connected to the control end of the switch tube Q2, and the second end of the switch tube Q3 is grounded; The flow regulation circuit (2) comprises a DAC chip U6 and two drive circuits with the same circuit structure, wherein one drive circuit comprises an operational amplifier U8B, a resistor R24, a resistor R23, a switch tube Q5 and a resistor R20. The clock end, data input end and data output end of the DAC chip U6 are all connected to the main control chip, the reference voltage input end of the DAC chip U6 is connected to the reference voltage Ref, the first analog output end of the DAC chip U6 is connected to the first end of the resistor R24, the second end of the resistor R24 ​​is grounded through the resistor R23, the second end of the resistor R24 ​​is connected to the in-phase input end of the operational amplifier U8B, the inverting input end of the operational amplifier U8B is grounded, the output end of the operational amplifier U8B is connected to the control end of the switch tube Q5, the first end of the switch tube Q5 is connected to the power supply 12V, the second end of the switch tube Q5 is used to connect to the first end of the first electric regulating valve coil, the first end of the resistor R20 is used to be connected to the second end of the first electric regulating valve coil, and the second end of the resistor R20 is grounded; The slurry flow detection circuit (3) comprises a slurry flow meter and a slurry flow meter power supply circuit. The slurry flow meter is used to detect the slurry flow. The output of the slurry flow meter is connected to the main control chip. The slurry flow meter power supply circuit includes an operational amplifier U4A and an operational amplifier U4B connected in sequence, the inverting input terminal of the operational amplifier U4A is connected to the third output terminal of the DAC chip U6 through a resistor R16, the output terminal of the operational amplifier U4A is feedback-connected to the inverting input terminal of the operational amplifier U4A through a resistor R11, the non-inverting input terminal of the operational amplifier U4A is grounded, the output terminal of the operational amplifier U4A is connected to the inverting input terminal of the operational amplifier U4B through a resistor R10, the output terminal of the operational amplifier U4B is feedback-connected to the inverting input terminal of the operational amplifier U4B through a resistor R9, the non-inverting input terminal of the operational amplifier U4B is grounded, and the output terminal of the operational amplifier U4B is used as the output of the slurry flow meter power supply circuit and is connected to the power supply terminal of the slurry flow meter; The slurry concentration detection circuit (4) comprises an ultrasonic concentration detector, a resistor R13 and an operational amplifier U5 which are connected in sequence. The ultrasonic concentration detector is used to detect the slurry concentration. The first end of the resistor R13 is connected to the output end of the ultrasonic concentration detector, the second end of the resistor R13 is grounded, the first end of the resistor R13 is connected to the inverting input end of the operational amplifier U5, the non-inverting input end of the operational amplifier U5 is grounded, the output end of the operational amplifier U5 is feedback-connected to the inverting input end of the operational amplifier U5, and the output end of the operational amplifier U5 is used as the output of the slurry concentration detection circuit (4) and is connected to the main control chip.

2. The automatic control system for coal slime flotation according to claim 1, characterized in that: The capacitor C1 is also included. A first end of the capacitor C1 is connected to a power source VCC via a resistor R2, and a second end of the capacitor C1 is grounded.

3. The automatic control system for coal slime flotation according to claim 1, characterized in that: The first end of the resistor R2, the anode of the laser diode LD1 and the cathode of the photodiode D1 are connected at one point, the anode of the laser diode LD1 and the power supply VCC are connected via a switch tube Q1, and a comparator U2 and an OR gate U1 are also included. The non-inverting input terminal of the comparator U2 is connected to the anode of the photodiode D1, the inverting input terminal of the comparator U2 is connected to the reference voltage VREF, the output terminal of the comparator U2 is connected to the first input terminal of the OR gate U1, the second input terminal of the OR gate U1 is connected to the first output terminal of the main control chip, the output terminal of the OR gate U1 is connected to the control terminal of the switch tube Q1, the first terminal of the switch tube Q1 is connected to the power supply VCC, and the second terminal of the switch tube Q1 is connected to the anode of the laser diode LD1.

4. The automatic control system for coal slime flotation according to claim 3, characterized in that: It also includes a resistor R6 and a resistor R7, wherein the first end of the resistor R6 is connected to the power supply 5V, the second end of the resistor R6 is grounded through the resistor R7, and the second end of the resistor R6 is used as the reference voltage VREF and connected to the inverting input end of the comparator U2.

5. The automatic control system for coal slime flotation according to claim 1, characterized in that: It also includes a reference voltage chip U7, the power supply end of the reference voltage chip U7 is connected to the power supply 5V, and the output end of the reference voltage chip U7 is used as the reference voltage Ref and connected to the reference voltage input end of the DAC chip U6.

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