CN110894010A

CN110894010A - Dust storage and separation equipment for sand conveyor

Info

Publication number: CN110894010A
Application number: CN201911242851.6A
Authority: CN
Inventors: 许海波
Original assignee: Suining Mingqiang Commercial Concrete Co Ltd
Current assignee: Suining Mingqiang Commercial Concrete Co Ltd
Priority date: 2019-12-06
Filing date: 2019-12-06
Publication date: 2020-03-20

Abstract

The invention discloses a dust collecting and separating device for a sand conveyor, which comprises a conveyor body and a dust collecting and separating mechanism connected with the conveyor body, wherein the dust collecting and separating mechanism comprises a dust collecting mechanism body and a dust collecting mechanism body; the method is characterized in that: the dust collecting and separating mechanism comprises a mounting frame (1), a dust collecting cover (11), a dust separating mechanism, a dust collecting device, an exhaust fan (3) and a controller (2). The dust collecting and separating mechanism is connected with the conveying machine body, and a dust hood in the dust collecting and separating mechanism can prevent the sand-stone conveying machine from raising dust to pollute the environment when conveying sand-stones; meanwhile, the dust separation mechanism in the mechanism is matched with the dust collection device and the exhaust fan, so that cement ash and fine sand in dust can be effectively separated, and the cement ash and the fine sand in the dust can be reused, so that the harm of the dust raised to a human body when the sand and stone are conveyed is reduced, the cement ash and the fine sand of the dust are effectively collected, and the resource loss is well prevented.

Description

Dust storage and separation equipment for sand conveyor

Technical Field

The invention relates to the technical field of concrete production, and particularly provides dust storage and separation equipment for a sand conveyor.

Background

With the rapid development of the building industry, the number of concrete mixing stations is increasing. The concrete mixing plant is composed of a plurality of fixed mixing devices, a blanking tank and a sand conveyor. And present grit conveyer all can raise a large amount of dust when transporting the grit, has existing cement ash in this dust, also has the fine sand. Therefore, when the sand conveyor conveys sand, dust is raised, so that the health of operators can be harmed, a large amount of resources can be lost, and meanwhile, the environment pollution can be caused.

At present, a lot of mixing plants adopt the canopy body to cover the grit conveyer, so although can effectually prevent that the grit conveyer from raising dust when transmitting the grit to environmental pollution, also play certain cement ash and the collection effect of fine sand to dust, operator health has received bigger injury.

Therefore, it is an urgent task to provide a dust collecting and separating device of a sand conveyor which can reduce the damage of dust to a human body when sand is conveyed and can effectively collect cement ash and fine sand of the dust.

Disclosure of Invention

The invention aims to overcome the defects that the dust generated by the sand-stone conveyor in the working process can not only harm the health of operators, but also cause a large amount of resource loss and environmental pollution, and provides the dust collecting and separating device of the sand-stone conveyor, which can reduce the damage of dust generated by raising dust to human bodies when sand-stones are conveyed and can also effectively collect cement dust and fine sand of the dust.

The purpose of the invention is realized by the following technical scheme: the utility model provides a splitter is accomodate to dust for grit conveyer, includes the conveying organism, accomodates the separating mechanism with the dust that the conveying organism is connected, separating mechanism is accomodate to dust includes the mounting bracket, the dust cage of being connected with the conveying organism, sets up on the mounting bracket with the dust separating mechanism of dust cage intercommunication, with the dust collecting device of dust separating mechanism intercommunication, install on the mounting bracket and with the air exhauster of dust collecting device intercommunication to and be used for controlling the controller of air exhauster.

The controller comprises a transformer T, an overvoltage protection circuit connected with a primary side inductance coil L1 of the transformer T, a voltage stabilizing circuit connected with a primary side inductance coil L2 of the transformer T, a current buffer circuit and a driving circuit respectively connected with a secondary side inductance coil L3 of the transformer T, and an adjustable potentiometer RP connected between a non-homonymous end of the primary side inductance coil L2 of the transformer T and the driving circuit in series; the adjustable potentiometer RP is connected with the current buffer circuit; the driving circuit is also connected with the current buffer circuit.

Furthermore, the dust separating mechanism comprises a cyclone separator and a pipeline, wherein one end of the pipeline is communicated with the dust collecting cover, and the other end of the pipeline is communicated with the cyclone separator; the cyclone separator is communicated with the dust collecting device through a connecting pipe; (ii) a And the mounting frame is also provided with a movable receiving barrel positioned below the discharge hole of the cyclone separator.

The dust collecting device comprises a dust collecting box with an air inlet and a dust suction port, an asbestos screen plate arranged in the dust collecting box through a fixing groove, and a dust guard plate which is arranged at the air inlet of the dust collecting box through a clamping groove and is positioned in the dust collecting box; the air inlet of the cyclone separator is connected with the dust suction port of the dust collection box, and the exhaust fan is connected with the air inlet of the dust collection box.

Preferably, the asbestos screen plate is obliquely arranged, and an acute angle formed between the asbestos screen plate and a horizontal plane is 30-60 degrees; the asbestos screen plate is positioned between the air inlet and the dust suction port of the dust collection box.

Still further, the overvoltage protection circuit comprises a triode Q1, a zener diode D1 with a P pole connected with the base of the triode Q1 and an N pole connected with the end with the same name of the primary inductance coil L1 of the transformer T, and a polar capacitor C1 with an anode connected with the emitter of the triode Q1 and a cathode connected with the end with the same name of the primary inductance coil L1 of the transformer T after passing through a resistor R2; the collector of the transistor Q1 is grounded, and the base of the transistor Q1 is used as the input terminal of the overvoltage protection circuit.

The voltage stabilizing circuit comprises a field effect transistor MOS1, a diode D2, a resistor R1, one end of which is connected with the N pole of the diode D2 and the other end of which is used as the input end of the current regulating circuit, a polar capacitor C2, the cathode of which is connected with the grid of the field effect transistor MOS1 and the anode of which is grounded, a diode D3, the P pole of which is connected with the anode of the polar capacitor C2 and the N pole of which is connected with the drain of the field effect transistor MOS1 after passing through a resistor R3, a diode D4, the P pole of which is connected with the source of the field effect transistor MOS1 and the N pole of which is connected with the density of a primary side inductance coil L1 of the transformer T, and a polar capacitor C3, the anode of which is connected with the P pole of the diode D36; and the drain electrode of the field effect transistor MOS1 is connected with the non-dotted terminal of a primary inductance coil L2 of the transformer T and then is connected with an input pin R of the adjustable potentiometer RP.

Furthermore, the current buffer circuit comprises a triode Q2, a triode Q4, an adjustable resistor R5 with one end connected with the base of a triode Q2 and the other end connected with an output pin D of an adjustable potentiometer RP, a diode D6 with a P pole connected with the output pin D of the adjustable potentiometer RP and an N pole grounded, a resistor R6 with one end connected with the emitter of the triode Q2 and the other end connected with the N pole of a diode D6, and a polar capacitor C5 with an anode connected with the ground of the triode Q2 and a cathode connected with the N pole of a diode D6; the base electrode of the triode Q4 is connected with the collector electrode of the triode Q2, the emitter electrode of the triode Q4 is connected with the end with the same name of the secondary side inductance coil L3 of the transformer T, and the collector electrode of the triode Q4 is connected with the driving circuit; the N pole of the diode D6 is connected with the driving circuit.

The driving circuit comprises a triode Q3, a triode Q5, a resistor R7 with one end connected with the collector of the triode Q4 and the other end connected with the collector of the triode Q3, a diode D5 with the P pole connected with the base of the triode Q5 and the N pole connected with the collector of the triode Q3 after passing through a resistor R8, a polar capacitor C4 with the negative pole connected with the collector of the triode Q3 and the positive pole connected with the non-name end of a secondary inductance coil L3 of a transformer T after passing through an inductance L2, a capacitor C5 with the positive pole connected with the base of the triode Q3 and the negative pole connected with an exhaust fan, and a resistor R9 with one end connected with the emitter of the triode Q3 and the other end connected with the exhaust fan; the emitter of the triode Q3 is connected with the N pole of the diode D6; the emitter of the transistor Q5 is connected to the output pin C of the adjustable potentiometer RP, and the collector of the transistor Q5 is grounded.

Preferably, the adjustable potentiometer RP is a BSS48LT1G single-turn potentiometer.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the dust collecting and separating mechanism is connected with the conveying machine body, and a dust hood in the dust collecting and separating mechanism can prevent the sand-stone conveying machine from raising dust to pollute the environment when conveying sand-stones; meanwhile, the dust separation mechanism in the mechanism is matched with the dust collection device and the exhaust fan, so that cement ash and fine sand in dust can be effectively separated, and the cement ash and the fine sand in the dust can be reused, so that the harm of the dust raised to a human body when the sand and stone are conveyed is reduced, the cement ash and the fine sand of the dust are effectively collected, and the resource loss is well prevented.

(2) The overvoltage protection circuit arranged in the controller can effectively protect the transformer when the load of the exhaust fan is increased, namely the armature current of the exhaust fan is increased, so that the working stability of the invention is well ensured.

(3) The buffer protection circuit arranged in the controller can restrain the current rise rate generated by the instant conduction of the transformer; meanwhile, the diode is combined with the sliding resistor, so that the voltage rising rate can be well inhibited, and the working stability of the whole system is ensured.

(4) The driving circuit in the controller provided by the invention realizes the purpose of providing stable driving current for the exhaust fan, further improves the working stability of the exhaust fan and effectively ensures the use stability of the controller.

Drawings

Fig. 1 is an overall structural view of the present invention.

Fig. 2 is a schematic diagram of the current structure of the controller according to the present invention.

The reference numbers in the drawings are:

1-mounting bracket, 2-controller, 3-air exhauster, 4-dust-collecting box, 5-cyclone, 6-dust guard, 7-asbestos otter board, 8-receipts storage bucket, 9-draw-in groove, 10-fixed slot, 11-dust cage, 12-pipeline, 13-unloading mechanism, 14-support, 15-transport mechanism, 16-pay-off case.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Examples

As shown in fig. 1, the dust collecting and separating device for a sand conveyor of the present invention comprises a conveyor body, a dust collecting and separating mechanism connected with the conveyor body; the conventional conveying machine body is adopted in the conveying machine body of the invention, and generally comprises a bracket 14, a blanking mechanism 13 and a feeding box 16 which are arranged on the bracket 14, a conveying mechanism 15 which is arranged in the feeding box 16 and is connected with the blanking mechanism 13, and the like. Since the transmission body is the prior art, the structure thereof will not be described herein. The present invention is directed to a dust housing and separating mechanism, and the structure of the dust housing and separating mechanism will be described below with emphasis on the description.

This separation mechanism is accomodate to dust is shown in fig. 1, and it includes mounting bracket 1, the dust cage 11 that is connected of being connected with the conveying organism, the dust separating mechanism who sets up on mounting bracket 1 and with the 11 intercommunications of dust cage, with the dust collecting device of dust separating mechanism intercommunication, install on mounting bracket 1 and with the air exhauster 3 of dust collecting device intercommunication to and the controller 2 that is used for controlling air exhauster 3. Specifically, the mounting frame 1 is fixed on the ground within the use range of the conveyor body by screws. The dust cage 11 is fixed on the box opening wall of the feeding box 16 through screws, the dust cage 11 and the feeding box 16 are matched to form a closed cavity, raised dust is closed in the cavity formed by the dust cage 11 and the feeding box 16 during conveying, and dust is effectively prevented from overflowing to pollute the environment. The separating mechanism and the exhaust fan 3 are fixed on the mounting frame 1 through screws. The power of the exhaust fan 3 and the size of the dust collection cover 11 are determined according to the capacity of the feed box 16 of the conveyor body, and the larger the capacity of the feed box 16 is, the larger the power of the exhaust fan 3 is, and the larger the volume of the dust collection cover 11 is, and conversely, the smaller the capacity of the feed box 16 is, the smaller the power of the exhaust fan 3 is, and the smaller the volume of the dust collection cover 11 is.

As shown in fig. 1, the dust separating mechanism includes a cyclone 5, and a duct 12 having one end communicating with a dust collection cover 15 and the other end communicating with the cyclone 5. The cyclone separator 5 is communicated with a dust collecting device through a connecting pipe; the mounting rack 1 is also provided with a movable receiving barrel 8 positioned below the discharge hole of the cyclone separator 5. Specifically, the cyclone separator 5 is realized by adopting the traditional XLT/A type bypass type cyclone separator, and the invention utilizes the characteristic that the cyclone separator 5 can remove solid particles with the particle size of more than or equal to 10 mu m, the separation efficiency is 99% at the working point and is 97% within the range of +/-15% at the working point, so as to ensure that the invention can effectively and accurately separate cement ash and fine sand in dust.

Meanwhile, the dust collecting device comprises a dust collecting box 4 with an air inlet and a dust suction port, an asbestos screen plate 7 arranged in the dust collecting box 4 through a fixing groove 10, and a dust guard 6 which is arranged at the air inlet of the dust collecting box 4 through a clamping groove 9 and is positioned in the dust collecting box 4; an air inlet of the cyclone separator 5 is connected with a dust suction port of the dust collection box 4, and the exhaust fan 3 is connected with an air inlet of the dust collection box 4. In order to reduce the adhesion of a large amount of cement ash to the asbestos gauge sheet 7, the asbestos gauge sheet 7 is arranged in an inclined manner, and an acute angle formed between the asbestos gauge sheet 7 and a horizontal plane is 30-60 degrees. The asbestos screen plate 7 is positioned between the air inlet and the dust suction port of the dust collection box 4.

When the dust collector operates, the exhaust fan 3 is opened through the controller 2, the exhaust fan 3 generates suction force, the suction force reaches the cyclone separator 5 through the dust suction port of the dust collection box 4, the cyclone separator 5 generates a large enough suction force for dust in the dust collection cover 11, the dust in the feeding box 16 enters the cyclone separator 5 through the pipeline 12, the fine sand in the cyclone separator 5 falls into the spiral discharging channel of the cyclone separator 5, and the dust enters the material receiving barrel 8 from the discharging port of the cyclone separator 5 to be used for the second time. The cement ash enters the dust collection box 4 under the action of suction force and sinks to the dust collection box 4 under the action of the asbestos screen plate 7 to be recycled. Therefore, the invention realizes the technical effects of reducing the damage of dust to human bodies when the sand stones are conveyed, effectively collecting cement ash and fine sand of the dust and well preventing resource loss.

As shown in fig. 2, the controller 2 includes a transformer T, an overvoltage protection circuit connected to a primary inductor L1 of the transformer T, a voltage regulator circuit connected to a primary inductor L2 of the transformer T, a current buffer circuit and a driving circuit respectively connected to a secondary inductor L3 of the transformer T, and an adjustable potentiometer RP connected in series between a non-dotted terminal of the primary inductor L2 of the transformer T and the driving circuit; the adjustable potentiometer RP is connected with the current buffer circuit; the driving circuit is also connected with the current buffer circuit. Specifically, the adjustable potentiometer RP is preferably implemented by a BSS48LT1G single-turn potentiometer.

Further, the overvoltage protection circuit comprises a transistor Q1, a polar capacitor C1, a resistor R2 and a zener diode D1.

When the transformer T primary side inductance coil L1 is connected, the pole of the voltage-stabilizing diode D1P is connected with the base electrode of the triode Q1, and the pole N is connected with the end with the same name of the primary side inductance coil L1 of the transformer T. The positive pole of the polar capacitor C1 is connected with the emitter of the triode Q1, and the negative pole of the polar capacitor C1 is connected with the end with the same name of the primary inductance coil L1 of the transformer T after passing through the resistor R2. The collector of the transistor Q1 is grounded, and the base of the transistor Q1 is used as the input terminal of the overvoltage protection circuit.

The resistor R2 is a forward resistor of the transformer T, and the resistor R1 is 2k omega; the capacitor C1 is used as the energy storage element of the present circuit, and the capacitance value is preferably set to 0.1 μ F. The non-dotted terminal and the non-dotted terminal of the inductor L1 of the transformer T obtain two reference potentials: one path of voltage output by a diode Q1 is directly transmitted to the same-name end of an inductance coil L1 of a transformer T through a polar capacitor C1 and a resistor R2; the collector of the second triode Q1 is divided, i.e. released to ground, so that the transformer T is not burned by the instantaneous high current generated when it is turned on.

As shown in fig. 2, the voltage stabilizing circuit includes a field effect transistor MOS1, a diode D2, a resistor R1, a resistor R3, a resistor R4, a diode D2, a diode D3, a diode D4, a polar capacitor C2, and a polar capacitor C3.

When connected, one end of the resistor R1 is connected to the N-pole of the diode D2, and the other end serves as an input terminal of the current regulating circuit. The cathode of the polar capacitor C2 is connected with the gate of the field effect transistor MOS1, and the anode is grounded. The P pole of the diode D3 is connected with the positive pole of the polar capacitor C2, and the N pole is connected with the drain of the field effect transistor MOS1 after passing through the resistor R3. The P pole of the diode D4 is connected to the source of the fet MOS1, and the N pole is connected to the density of the primary inductor L1 of the transformer T. The anode of the polar capacitor C3 is connected to the P-pole of the diode D3 through the resistor R4, and the cathode is connected to the cathode of the polar capacitor C2. And the drain electrode of the field effect transistor MOS1 is connected with the non-dotted terminal of a primary inductance coil L2 of the transformer T and then is connected with an input pin R of the adjustable potentiometer RP.

The resistor R1 is a forward resistor of the diode D2, and the resistor R1 is the resistor R3 is 10k Ω; the resistor R3 is a resistor R1 and a resistor R3, and the resistor R3 is 10k Ω; the capacitor C3 is used as the current release element of the present circuit, and the capacitance is preferably set to 22 μ F.

Furthermore, the current buffer circuit comprises a transistor Q2, a transistor Q4, an adjustable resistor R5, a resistor R6, a diode D6 and a polar capacitor C5.

When the adjustable resistor R5 is connected, one end of the adjustable resistor R5 is connected with the base of the triode Q2, and the other end of the adjustable resistor R5 is connected with the output pin D of the adjustable potentiometer RP. The P pole of the diode D6 is connected with the output pin D of the adjustable potentiometer RP, and the N pole is grounded. One end of the resistor R6 is connected to the emitter of the transistor Q2, and the other end is connected to the N-pole of the diode D6. The anode of the polar capacitor C5 is connected to the ground of the transistor Q2, and the cathode is connected to the N-pole of the diode D6. The base electrode of the triode Q4 is connected with the collector electrode of the triode Q2, the emitter electrode of the triode Q4 is connected with the end with the same name of the secondary side inductance coil L3 of the transformer T, and the collector electrode is connected with the driving circuit; the N pole of the diode D6 is connected with the driving circuit.

The three headers Q2 in the embodiment adopt 3DG 12; meanwhile, the adjustable range of the resistance value of the adjustable resistor R5 is 0-4.7 k omega, the resistor R6 is used as a cut-off resistor, and the resistance value is set to 47k omega; the polarity capacitor C5 is used as a trigger capacitor which is 2200 μ F charge-discharge capacitance with high capacitance value; the diode D6 preferably uses a 1N4148 switch tube.

When the output voltage of the transformer T is increased, the resistor R6 starts to reduce the voltage, the potential of the adjustable resistor R5 is reduced, the triode Q2 is conducted, the collector output of the triode Q2 is 0V, the base of the triode Q4 is set to be reduced in level, and the voltage is pulled down by the polar capacitor C5. When the output voltage of the transformer T is reduced, the potential of the adjustable resistor R5 rises, the triode Q2 is cut off, the collector output of the triode Q2 is 1V, the triode Q4 is conducted, and the collector voltage of the triode Q4 rises to ensure the normal work of the exhaust fan 3, so that the working reliability of the exhaust fan is effectively ensured.

As shown in fig. 2, the driving circuit includes a transistor Q3, a transistor Q5, a resistor R7, a resistor R8, a resistor R9, a diode D5, a polar capacitor C4, and a capacitor C5.

When connected, the resistor R7 has one end connected to the collector of the transistor Q4 and the other end connected to the collector of the transistor Q3. The P pole of the diode D5 is connected with the base of the transistor Q5, and the N pole is connected with the collector of the transistor Q3 after passing through the resistor R8. The negative electrode of the polar capacitor C4 is connected with the collector of the triode Q3, and the positive electrode of the polar capacitor C4 is connected with the non-name end of the secondary inductance coil L3 of the transformer T after passing through the inductance L2. The anode of the capacitor C5 is connected with the base of the triode Q3, and the cathode is connected with the exhaust fan 3. Resistor R9 has one end connected to the emitter of transistor Q3 and the other end connected to suction fan 3. The emitter of the triode Q3 is connected with the N pole of the diode D6; the emitter of the transistor Q5 is connected to the output pin C of the adjustable potentiometer RP, and the collector of the transistor Q5 is grounded.

In the embodiment, the triode Q3 and the triode Q5 both preferentially adopt 3DG12, and the three collecting pipes Q4 are realized by adopting amplifying pipes with the model number of 3AX 81; the resistance value of the resistor R7 is set to 4.7k omega, the resistance value of the resistor R8 is set to 4k omega, and the resistance value of the resistor R9 is set to 1k omega; the inductance value of the inductor L4 was set to 50 μ H; the capacitance of the polar capacitor C4 is set to 2.2 μ F, the capacitance of the capacitor C5 is set to 22 μ F, and the diode D5 is preferably implemented by 1N 4018. The resistor R8 and the resistor R9 are used as sampling resistors.

In operation, when the collector of the triode Q2 is at a high level of 1V, the three-manifold Q3 is turned on, the base of the three-manifold Q5 is at a high level, the diode D5 is also turned on, the inductor L4 and the polar capacitor C4 form a galvanostat, so as to ensure that a stable working voltage is provided for the exhaust fan 3, at this time, the exhaust fan 3 is powered on, the exhaust fan 3 is in a high-speed working state, and simultaneously, the polar capacitor C5 starts to charge. When the collector of the triode Q2 is at low level of 0V, the triple tube Q3 is cut off, the diode D5 is cut off, the polar capacitor C5 of the exhaust fan 3 starts to discharge, at this time, the exhaust fan 3 rotates at low speed for about 10 seconds by means of the stored energy of the consistency and polar capacitor C5, and the dust which has entered the cyclone separator 5 after the exhaust fan 3 stops rotating at high speed is separated. Therefore, the use effect of the invention is effectively ensured, stable driving current is provided for the exhaust fan 3, the working stability of the exhaust fan 3 is further improved, and the use stability of the invention is effectively ensured.

As described above, the present invention can be well implemented.

Claims

1. A dust collecting and separating device for a sand conveyor comprises a conveyor body and a dust collecting and separating mechanism connected with the conveyor body; the method is characterized in that: the dust collecting and separating mechanism comprises a mounting frame (1), a dust collecting cover (11) connected with the conveying machine body, a dust separating mechanism arranged on the mounting frame (1) and communicated with the dust collecting cover (11), a dust collecting device communicated with the dust separating mechanism, an exhaust fan (3) arranged on the mounting frame (1) and communicated with the dust collecting device, and a controller (2) used for controlling the exhaust fan (3); the controller (2) comprises a transformer T, an overvoltage protection circuit connected with a primary inductance coil L1 of the transformer T, a voltage stabilizing circuit connected with a primary inductance coil L2 of the transformer T, a current buffer circuit and a driving circuit respectively connected with a secondary inductance coil L3 of the transformer T, and an adjustable potentiometer RP connected between a non-homonymous end of the primary inductance coil L2 of the transformer T and the driving circuit in series; the adjustable potentiometer RP is connected with the current buffer circuit; the driving circuit is also connected with the current buffer circuit.

2. A dirt receiving and separating apparatus for a sand conveyor as claimed in claim 1, wherein: the dust separating mechanism comprises a cyclone separator (5) and a pipeline (12) of which one end is communicated with the dust collecting cover (11) and the other end is communicated with the cyclone separator (5); the cyclone separator (5) is communicated with a dust collecting device through a connecting pipe; the mounting rack (1) is also provided with a receiving barrel (8) which is movable and is positioned below the discharge hole of the cyclone separator (5).

3. A dirt receiving and separating apparatus for a sand conveyor as claimed in claim 2, wherein: the dust collecting device comprises a dust collecting box (4) with an air inlet and a dust suction port, an asbestos screen plate (7) arranged in the dust collecting box (4) through a fixing groove (10), and a dust guard (6) which is arranged at the air inlet of the dust collecting box (4) through a clamping groove (9) and is positioned in the dust collecting box (4); an air inlet of the cyclone separator (5) is connected with a dust suction port of the dust collection box (4), and the exhaust fan (3) is connected with an air inlet of the dust collection box (4).

4. A dirt receiving and separating apparatus for a sand conveyor as claimed in claim 3, wherein: the asbestos screen plate (7) is obliquely arranged, and an acute angle formed by the asbestos screen plate and a horizontal plane is 30-60 degrees; the asbestos screen plate (7) is positioned between the air inlet and the dust suction port of the dust collection box (4).

5. A dust collecting and separating apparatus for a sand conveyor as claimed in any one of claims 1 to 4, wherein: the overvoltage protection circuit comprises a triode Q1, a voltage stabilizing diode D1 of which the P pole is connected with the base electrode of the triode Q1 and the N pole is connected with the non-dotted terminal of a primary inductance coil L1 of the transformer T, and a polar capacitor C1 of which the anode is connected with the emitter electrode of the triode Q1 and the cathode is connected with the dotted terminal of a primary inductance coil L1 of the transformer T after passing through a resistor R2; the collector of the transistor Q1 is grounded, and the base of the transistor Q1 is used as the input terminal of the overvoltage protection circuit.

6. A dust receiving and separating apparatus for a sand conveyor as claimed in claim 5, wherein: the voltage stabilizing circuit comprises a field effect transistor MOS1, a diode D2, a resistor R1, one end of which is connected with the N pole of the diode D2 and the other end of which is used as the input end of the current regulating circuit, a polar capacitor C2, the cathode of which is connected with the grid of the field effect transistor MOS1 and the anode of which is grounded, a diode D3, the P pole of which is connected with the anode of the polar capacitor C2 and the N pole of which is connected with the drain of the field effect transistor MOS1 after passing through a resistor R3, a diode D4, the P pole of which is connected with the source of the field effect transistor MOS1 and the N pole of which is connected with the density of a primary side inductance coil L1 of the transformer T, and a polar capacitor C3, the anode of which is connected with the P pole of the diode D36; and the drain electrode of the field effect transistor MOS1 is connected with the non-dotted terminal of a primary inductance coil L2 of the transformer T and then is connected with an input pin R of the adjustable potentiometer RP.

7. A dust receiving and separating apparatus for a sand conveyor as claimed in claim 6, wherein: the current buffer circuit comprises a triode Q2, a triode Q4, an adjustable resistor R5 with one end connected with the base of a triode Q2 and the other end connected with an output pin D of an adjustable potentiometer RP, a diode D6 with a P pole connected with the output pin D of the adjustable potentiometer RP and an N pole grounded, a resistor R6 with one end connected with the emitter of the triode Q2 and the other end connected with the N pole of a diode D6, and a polar capacitor C5 with an anode connected with the ground of a triode Q2 and a cathode connected with the N pole of a diode D6; the base electrode of the triode Q4 is connected with the collector electrode of the triode Q2, the emitter electrode of the triode Q4 is connected with the end with the same name of the secondary side inductance coil L3 of the transformer T, and the collector electrode of the triode Q4 is connected with the driving circuit; the N pole of the diode D6 is connected with the driving circuit.

8. A dirt receiving and separating apparatus for a sand conveyor as claimed in claim 7, wherein: the driving circuit comprises a triode Q3, a triode Q5, a resistor R7 with one end connected with the collector of the triode Q4 and the other end connected with the collector of the triode Q3, a diode D5 with the P pole connected with the base of the triode Q5 and the N pole connected with the collector of the triode Q3 after passing through a resistor R8, a polar capacitor C4 with the negative pole connected with the collector of a triode Q3 and the positive pole connected with the non-name end of a secondary inductance coil L3 of a transformer T after passing through an inductance L2, a capacitor C5 with the positive pole connected with the base of the triode Q3 and the negative pole connected with an exhaust fan (3), and a resistor R9 with one end connected with the emitter of the triode Q3 and the other end connected with the exhaust fan (3); the emitter of the triode Q3 is connected with the N pole of the diode D6; the emitter of the transistor Q5 is connected to the output pin C of the adjustable potentiometer RP, and the collector of the transistor Q5 is grounded.

9. A dirt receiving and separating apparatus for a sand conveyor as claimed in claim 8, wherein: the adjustable potentiometer RP is a BSS48LT1G single-turn potentiometer.