Open-pit mine dust control device and clean coal caving method

Abstract

The invention belongs to the field of dust prevention and removal devices and methods for open-pit mines, and particularly relates to a dust control device for an open-pit mine and a clean coal caving method.The dust control device for the open-pit mine comprises a coal caving opening formed in a floor, a telescopic chute is arranged on the lower portion of the coal caving opening, the upper portion of the telescopic chute is fixed to the coal caving opening, and a dust suction hood is fixed to the lower portion in the circumferential direction; a hydraulic telescopic rod and a telescopic air channel are arranged between the dust hood and a floor, a ventilation air channel penetrating through the end of the floor is connected with a flat bag dust collector, the flat bag dust collector is connected with a negative pressure centrifugal fan, and a laser range finder is installed at the bottom of the dust hood. According to the clean coal caving method, the working gear of the negative pressure centrifugal fan can be adjusted in real time according to the distance between the dust hood and the coal pile in the coal caving process, and efficient and energy-saving treatment on dust pollution of the coal caving opening can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of dust prevention and removal devices and methods for open-pit mines (E21F5 / 00), and in particular relates to a dust control device and a clean coal placing method for open-pit mines. Background Art

[0002] Coal is an important basic energy source. There are a lot of transfer processes in the coal mine production and transportation system, and a lot of dust is generated during these processes. The coal discharge port of the open-pit mine coal transportation system will generate a lot of dust during the coal loading process, which seriously pollutes the surrounding environment and endangers the health of workers.

[0003] At present, the existing chute equipment cannot adjust the distance between the chute and the carriage. The area of ​​the chute that is not covered by the dust cover is affected by the suction airflow, generating a large amount of dust. In the related technologies of negative pressure dust removal, the speed of the centrifugal fan is usually set at a fixed speed, or the speed adjustment is not timely enough, which makes the speed of the centrifugal fan unable to adapt to the dust conditions on site, resulting in waste of electricity or causing large dust problems. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes an open-pit mine dust control device and a clean coal discharge method, which adopts a telescopic chute-type dust control device and adjusts the working gear of the negative pressure centrifugal fan in real time according to the distance between the dust hood and the coal pile during the coal discharge process, thereby achieving efficient and energy-saving control of dust pollution at the coal discharge port.

[0005] Specifically, the mine dust control device includes a coal discharge port arranged on the floor, a telescopic chute is arranged at the lower part of the coal discharge port, the telescopic chute includes an inner chute and an outer chute which are hollow cylinders as a whole, the upper part of the inner chute is fixed to the coal discharge port, the inner diameter of the inner chute is consistent with the coal discharge port, and the outer chute can be slidably connected to the outside of the inner chute; a dust hood is fixed to the bottom circumference of the outer chute with the outer chute as the center, one end of a hydraulic telescopic rod is connected to the upper part of the dust hood, and the other end of the hydraulic telescopic rod is fixed to the floor; the dust hood is connected to the outer chute of the outer chute; One end of the telescopic air duct is fixed to the passage, the other end of the telescopic air duct is fixed on the floor slab and passes through the floor slab, and the end passing through the floor slab is connected to a flat bag dust collector through a ventilation air duct, and the flat bag dust collector is connected to a negative pressure centrifugal fan; a laser rangefinder is installed at the bottom of the dust hood; it also includes a controller, the controller is connected to the negative pressure centrifugal fan so as to control the working gear of the negative pressure centrifugal fan, and the controller is connected to the laser rangefinder to obtain data measured by the laser rangefinder; the negative pressure centrifugal fan includes multiple gears, and each gear corresponds to a different fan speed.

[0006] Preferably, a quantitative coal placing machine is arranged on the floor slab, and the quantitative coal placing machine is connected to the bottom of the silo and the coal placing port.

[0007] Preferably, an outward-turned boss is provided at the bottom of the inner chute, and an inward-turned constriction is provided at the top of the outer chute.

[0008] Preferably, the dust hood is rectangular, with the long side consistent with the width direction of the truck compartment and the short side consistent with the travel direction of the truck.

[0009] Preferably, two hydraulic telescopic rods are provided, symmetrically arranged on both sides of the telescopic chute, and two telescopic airways are provided, symmetrically arranged on both sides of the telescopic chute.

[0010] Preferably, the controller is connected to the hydraulic telescopic rod to control the extension and retraction of the hydraulic telescopic rod and obtain the extension and retraction length, and the controller is connected to the quantitative coal placing machine to control and obtain the coal placing rate of the quantitative coal placing machine.

[0011] Preferably, the negative pressure centrifugal fan is selected according to the optimal operating point of the maximum load.

[0012] The open-pit mine clean coal discharge method adopts the open-pit mine dust control device described above, and comprises the following steps:

[0013] S1. The empty truck drives to the lower part of the coal discharge port, controls the hydraulic telescopic rod to extend so that the bottom of the dust hood is flush with the top surface of the truck compartment, and obtains the vertical distance L between the bottom of the dust hood and the coal discharge port;

[0014] S2. The controller controls the negative pressure centrifugal fan to work, and the quantitative coal discharger starts to discharge coal to the coal discharge port at a coal discharge speed V. The laser rangefinder obtains the distance H′ between the dust hood and the coal pile in the truck compartment in real time;

[0015] S3. When H′≥the short side length b of the dust hood, the negative pressure centrifugal fan operates at the highest gear;

[0016] When H′<the short side length b of the dust hood, first use the following formula to calculate the required speed of the negative pressure centrifugal fan:

[0017]

[0018] Where n is the required negative pressure centrifugal fan speed, r / min; n max is the maximum speed of the negative pressure centrifugal fan, r / min; k is the control wind speed determination coefficient, which is 1.1; H′ is the distance between the dust hood and the coal pile in the truck compartment, m; S′ is the area of ​​the dust hood, m 2 ;Q max is the maximum air volume that the negative pressure centrifugal fan can provide when it is running, m 3 / s; η1 is the airway system efficiency, which is taken as 97%; η is the efficiency of coal pile converting work done on air into air kinetic energy, which is taken as 95%; C is the coal resistance coefficient, which is taken as 0.5; g is the acceleration of gravity, which is 9.8m / s 2, A is the cross-sectional area of ​​the coal falling process, m 2 , V is the coal discharge rate of the coal discharge machine, t / h, V max is the maximum coal discharge rate of the coal discharge machine, t / h, A max is the cross-sectional area of ​​coal on the caving machine belt at the maximum caving rate, m 2 ; L is the vertical distance between the bottom of the dust hood and the coal discharge port, m; H is the coal drop height, m, H = H' + L; S is the cross-sectional area of ​​the coal discharge port, m 2 ;

[0019] Then the controller controls the negative pressure centrifugal fan to switch to the lowest gear that satisfies the required negative pressure centrifugal fan speed n calculated by the above formula.

[0020] Preferably, when the gear of the negative pressure centrifugal fan needs to be lowered, it is lowered step by step and maintained at each gear for a certain time, and recalculated whether the gear needs to be further lowered until it is lowered to a suitable gear. When the gear of the negative pressure centrifugal fan needs to be raised, it is raised to the required gear at one time.

[0021] The present invention also seeks to protect an open-pit mine dust control device, which, in addition to the dust control device structure described above, also includes a calculation program, wherein the calculation program is used to execute the open-pit mine clean coal discharge method described above, and the open-pit mine dust control device switches the gear of the negative pressure centrifugal fan according to the calculation program.

[0022] The key means and beneficial effects of the present invention are:

[0023] 1. The telescopic chute structure can adapt to the coal loading work of trucks of various sizes. The corresponding telescopic chute extension length is implemented for trucks of different sizes to separate the falling coal from the working space, greatly reducing the impact of the entrained airflow on the coal, thereby effectively reducing the dust generated by the coal loading work;

[0024] 2. The fan control method can adapt to the on-site dust conditions and adjust the speed of the negative pressure centrifugal fan in real time. While ensuring the maximum dust reduction efficiency, it reduces power consumption and achieves efficient, energy-saving and clean coal discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the front and side views of the silo loading station of the present invention;

[0026] Figure 2 It is a schematic diagram of the open-pit mine dust control device of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the inner chute and the outer chute of the present invention;

[0028] Figure 4This is a schematic diagram of force analysis of the coal falling process of the present invention;

[0029] Figure 5 It is a schematic diagram of wind speed control of the present invention;

[0030] In the figure, silo bottom 1, truck 2, quantitative coal discharger 3, coal discharge port 4, hydraulic telescopic rod 5, inner chute 6, outer chute 7, laser rangefinder 8, dust hood 9, telescopic air duct 10, connecting air duct 11, flat bag dust collector 12, negative pressure centrifugal fan 13, controller 14, boss 15, necking 16, coal flow cylinder 17, simplified chute structure 18, air in the columnar body just below the coal discharge port 19, stockpile 20, and dust source point 21. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described in more detail below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] Embodiment 1

[0033] like Figure 1-3 As shown, the open-pit mine dust control device comprises a coal discharge port 4 arranged on the floor slab, and a quantitative coal discharger 3 is arranged on the floor slab, and the quantitative coal discharger 3 is connected to the silo bottom 1 and the coal discharge port 4, and quantitatively transfers the coal discharged from the silo bottom 1 to the coal discharge port 4;

[0034] A telescopic chute is provided at the coal discharge port 4 at the lower part of the floor slab. The telescopic chute includes an inner chute 6 and an outer chute 7 which are hollow cylinders as a whole. The upper part of the inner chute 6 is fixed at the coal discharge port. The inner diameter of the inner chute 6 is consistent with the coal discharge port 4. The outer chute 7 is slidably connected to the outside of the inner chute 6. An outward-turned boss 15 is provided at the bottom of the inner chute 6. An inward-turned constriction 16 is provided at the top of the outer chute 7. When the outer chute 7 slides to the lowest position, the constriction 16 clamps the boss 15.

[0035] A dust hood 9 is fixed to the bottom circumference of the outer chute 7 with the outer chute as the center, and one end of the hydraulic telescopic rod 5 is connected to the upper part of the dust hood 9, and the other end of the hydraulic telescopic rod 5 is fixed to the floor. Since the dust hood 9 is fixedly connected to the bottom of the outer chute 7, the hydraulic telescopic rod 5 can control the outer chute 7 to slide relative to the inner chute 6 by controlling the dust hood 9 to move up and down, thereby realizing the telescopic and length change of the telescopic chute; the dust hood 9 is connected and fixed with one end of a telescopic airway 10, and the other end of the telescopic airway 10 is fixed to the floor and passes through the floor, and the end passing through the floor passes through the ventilation airway 1 1 is connected to a flat bag dust collector 12, and the flat bag dust collector 12 is connected to a negative pressure centrifugal fan 13; the dust hood 9 can be circular or rectangular, and preferably rectangular. When a rectangle is used, the long side is consistent with the width direction of the truck compartment, and the short side is consistent with the moving direction of the truck, that is, the length direction of the truck compartment; the hydraulic telescopic rods 5 are provided with two, symmetrically arranged on both sides of the telescopic chute, and the telescopic air ducts 10 are provided with two, symmetrically arranged on both sides of the telescopic chute; a laser rangefinder 8 is installed at the bottom of the dust hood 9 for measuring the distance between the bottom end of the dust hood 9 and the bottom surface of the truck compartment 2 or the coal pile 20 in the truck compartment 2;

[0036] It also includes a controller 14, which is connected to the negative pressure centrifugal fan 13 so as to control the working gear of the negative pressure centrifugal fan 13, the controller 14 is connected to the hydraulic telescopic rod 5 to control the extension and retraction of the hydraulic telescopic rod 5 and obtain the extension length, the controller 14 is connected to the quantitative coal placing machine 3 to control and obtain the coal placing rate of the quantitative coal placing machine 3, and the controller 14 is connected to the laser rangefinder 8 to obtain the data measured by the laser rangefinder 8;

[0037] The negative pressure centrifugal fan 13 includes a plurality of gears, each gear corresponding to a different fan speed. The negative pressure centrifugal fan 13 is selected according to the optimal operating point of the maximum load.

[0038] Embodiment 2

[0039] The open-pit mine clean coal discharge method adopts the open-pit mine dust control device in the first embodiment, and comprises the following steps:

[0040] S1. The empty truck 2 drives to the lower part of the coal discharge port 4, and the controller 14 controls the hydraulic telescopic rod 5 to extend so that the bottom of the dust hood 9 is flush with the top surface of the truck compartment. The vertical distance L between the bottom of the dust hood 9 and the coal discharge port can be obtained according to the original length and telescopic length of the hydraulic telescopic rod;

[0041] S2. The controller 14 controls the negative pressure centrifugal fan 13 to start coal discharge. The coal is discharged from the bottom of the silo 1 to the quantitative coal discharger 3. The quantitative coal discharger 3 discharges the coal from the coal discharge port 4 and the telescopic chute to the truck compartment at a coal discharge speed V. During the coal discharge process, the laser rangefinder 8 obtains the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment in real time;

[0042] S3. When H′≥ the short side length b of the dust hood, the controller 14 controls the negative pressure centrifugal fan 13 to work at the highest gear;

[0043] When H′<the short side length b of the dust hood, firstly use the following formula to calculate the required speed of the negative pressure centrifugal fan 13:

[0044]

[0045] Where n is the required negative pressure centrifugal fan speed, r / min; n max is the maximum speed of the negative pressure centrifugal fan, r / min; k is the control wind speed determination coefficient, which is 1.1; H′ is the distance between the dust hood and the coal pile in the truck compartment, m; S′ is the area of ​​the dust hood, m 2 ;Q max is the maximum air volume that the negative pressure centrifugal fan can provide when it is running, m 3 / s; η1 is the efficiency of the airway system, about 97%; η is the efficiency of the coal pile converting the work done on the air into air kinetic energy, which is taken as 95%; C is the coal resistance coefficient, which is taken as 0.5; g is the acceleration of gravity, 9.8m / s 2 , A is the cross-sectional area of ​​the coal falling process, m 2 , V is the coal discharge rate of the coal discharge machine, t / h, V max is the maximum coal discharge rate of the coal discharge machine, t / h, A max is the cross-sectional area of ​​coal on the caving machine belt at the maximum caving rate, m 2 ; L is the vertical distance between the bottom of the dust hood and the coal discharge port, m; H is the coal drop height, m, H = H' + L; S is the cross-sectional area of ​​the coal discharge port, m 2 ;

[0046] The controller 14 controls the negative pressure centrifugal fan 13 to switch to the lowest gear that satisfies the required negative pressure centrifugal fan speed n calculated by the above formula; for example, the negative pressure centrifugal fan gears include N1, N2, N3...Ni, corresponding to fan speeds n1, n2, n3...ni, respectively. The required negative pressure centrifugal fan speed n is calculated according to the above formula. When n≤n1, the fan adopts the N1 gear; when n1<n≤n2, the fan adopts the N2 gear; when n2<n≤n3, the fan adopts the N3 gear.

[0047] Preferably, when the gear of the negative pressure centrifugal fan needs to be lowered, it is lowered step by step and the duration at each gear is not less than 3-5s. The gear is recalculated whether it needs to be further lowered until it is lowered to a suitable gear. When the gear of the negative pressure centrifugal fan needs to be raised, it is raised to the required gear at one time.

[0048] The derivation process of the formula in the second embodiment is as follows:

[0049] like Figure 4 As shown, the falling process of coal in the telescopic chute is simplified into a cylinder (coal flow cylinder 17), and the total resistance F is calculated as follows:

[0050]

[0051] Where F is the total resistance of the coal, N; C is the resistance coefficient of the coal, which is 0.5; A is the cross-sectional area of ​​the coal during its fall, m 2 , V is the coal discharge rate of the coal discharge machine, t / h, V max is the maximum coal discharge rate of the coal discharge machine, t / h, A max is the cross-sectional area of ​​coal on the caving machine belt at the maximum caving rate, m 2 ; u is the speed difference between the coal and the surrounding air, m / s. Assuming that the initial speed of the air around the coal is 0, the speed difference between the coal and the surrounding air is the falling speed of the coal. H is the falling height of coal, m, H=H′+L, g is the acceleration due to gravity, 9.8m / s 2 ; ρ is air density, kg / m 3 .

[0052] Since the inner diameter of the inner chute 6 is not much different from the inner diameter of the outer chute, the inner diameter of the telescopic chute is simplified to be consistent (see Figure 4 The simplified chute structure 18) is that the inner diameters of the coal discharge port 4, the inner chute 6, and the outer chute 7 are considered to be the same. The difference between the cross-sectional area of ​​the simplified chute structure 18 and the cross-sectional area of ​​the coal flow cylinder 17 is the flow area. The total resistance F is divided by the flow area to obtain the air resistance P of the coal. g :

[0053]

[0054] Where P g is the air resistance of the coal, Pa; S is the cross-sectional area of ​​the coal discharge port, m 2 .

[0055] According to the same action force and reaction force, the work W done by the coal on the air during the falling process is obtained by integration:

[0056]

[0057]

[0058] The work W done by the coal material on the air (the air in the column from the coal discharge port 3 to the top of the coal pile 20 with the inner diameter of the coal discharge port as the diameter, that is, the air 19 in the column directly below the coal discharge port) during the falling process is partially converted into the air kinetic energy W g :

[0059]

[0060] W g =ηW (6)

[0061]

[0062] Where, v is the air velocity, m / s, v m It is the maximum air velocity obtained after the coal does work on the air during the falling process, referred to as the maximum air velocity, which is the impact air flow velocity and also the dust precipitation velocity; η is the efficiency of the coal pile converting the work done on the air into air kinetic energy, which is taken as 95%.

[0063] In order to ensure that the dust is sucked into the dust hood 9, it is necessary to generate a wind speed of v at the dust source point 21. x The airflow changes the movement of the dust, causing the dust to move at a speed of v m The motion is transformed into a velocity v r And toward the dust cover 9, as Figure 5 As shown, the dust source point controls the wind speed v x for:

[0064] v x =kv m (8)

[0065] In the formula, v x is the controlled wind speed, m / s; k is the controlled wind speed determination coefficient, which is taken as 1.1.

[0066] When the vertical distance H from the bottom of the telescopic chute to the top of the pile is less than the short side b of the dust hood, the required suction air volume of the dust hood can be calculated according to the calculation formula of the air volume of the external rectangular hood:

[0067] Q=(10H′ 2 +S′)v x (9)

[0068] Where, Q is the air volume sucked into the dust hood, m 3 / s; H′ is the distance between the dust hood and the coal pile in the truck compartment, m; S′ is the area of ​​the dust hood, m 2 .

[0069] From equation (7), equation (8) and equation (9), we can get:

[0070]

[0071] The air volume provided by the negative pressure centrifugal fan is partially lost in the air duct system:

[0072] Q=η1Q c (11)

[0073] In the formula, Q c Air volume provided by centrifugal fan, m 3 / s; η1 is the airway system efficiency, about 97%.

[0074] The relationship between the speed and performance of the negative pressure centrifugal fan:

[0075]

[0076] According to equations (10), (11), (12), and the maximum performance parameters of the negative pressure centrifugal fan:

[0077]

[0078] Where n is the required negative pressure centrifugal fan speed, r / min; n max is the maximum speed of the negative pressure centrifugal fan, r / min; Q max is the maximum air volume of negative pressure centrifugal fan, m 3 / s.

[0079] Embodiment 3

[0080] The open-pit mine dust control device is as described in the first embodiment. In addition, the control device also includes a calculation program, and the calculation program is used to execute the method in the second embodiment. The control device switches the gear of the negative pressure centrifugal fan according to the calculation program.

[0081] Embodiment 4

[0082] Taking the Zhonglian Runshi silo loading station as an example, the open-pit mine dust control device described in Implementation 3 is adopted;

[0083] The coal discharge rate of the quantitative coal discharge machine 3 is 0-800t / h, that is, the maximum coal discharge rate of the quantitative coal discharge machine 3 is V max The belt width of the quantitative coal discharger 3 is 1m, and the height of the coal on the belt is 0.4m. That is, the cross-sectional area of ​​the coal on the belt of the quantitative coal discharger 3 at the maximum coal discharge rate is A. max 0.4m 2 The coal discharge port 4 is a circle with a diameter of 1.2m, that is, the cross-sectional area S of the coal discharge port 4 is 1.13m 2 The dust suction opening on the bottom of the dust suction hood 9 is rectangular in shape, with a long side a of 1.5 m and a short side b of 1.3 m, and an area S′ of 1.95 m2 The efficiency η1 of the connecting air duct 11 is measured to be 97%. The negative pressure centrifugal fan 13 adopts a 4-79-16e centrifugal fan, and the performance parameters of the 4-79-16e centrifugal fan are the maximum speed n max The maximum air volume is 740r / min. max 41.1m 3 / s; it is divided into 5 gears, namely N1, N2, N3, N4, N5. The fan speeds corresponding to the gears N1, N2, N3, N4, N5 are 290r / min, 370r / min, 470r / min, 580r / min, 740r / min respectively, that is, n1, n2, n3, n4, n5 are 290r / min, 370r / min, 470r / min, 580r / min, 740r / min respectively.

[0084] The empty truck 2 travels to the lower part of the coal discharge port 4, and the controller 14 controls the hydraulic telescopic rod 5 to extend so that the bottom of the dust hood 9 is flush with the top surface of the truck compartment. According to the original length and telescopic length of the hydraulic telescopic rod, the vertical distance L=0.8m between the bottom of the dust hood 9 and the coal discharge port can be obtained; the laser rangefinder 8 measures the distance H′=2.8m from the bottom of the dust hood 9 to the bottom of the truck compartment, and the coal falling height H is 3.6m.

[0085] The controller 14 controls the negative pressure centrifugal fan 13 to start discharging coal. The coal is discharged from the bottom 1 of the silo to the quantitative coal discharger 3. The quantitative coal discharger 3 discharges coal from the coal discharge port 4 and the telescopic chute to the truck compartment at a coal discharge rate of 800 t / h. During the coal discharge process, the laser rangefinder 8 obtains the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment in real time. When the distance H′ from the bottom of the dust hood 9 to the top of the pile 20 is ≥ the short length b of the dust hood 9, the negative pressure centrifugal fan 13 is in the highest gear N5.

[0086] As the coal loading work proceeds, when the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to 1.3m, the quantitative coal discharger 3 discharges coal at a rate of 800t / h, and the controller 14 calculates the required negative pressure centrifugal fan speed n=890, n>580, and the negative pressure centrifugal fan 13 continues to run at the N5 gear.

[0087] When the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to 1.05m, the quantitative coal discharger 3 discharges coal at a rate of 800t / h, and the controller 14 calculates the required speed of the negative pressure centrifugal fan n=575, 470<n≤580, and the negative pressure centrifugal fan 13 reduces the gear to N4.

[0088] When the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to 0.94 m, the quantitative coal discharger 3 discharges coal at a rate of 800 t / h, and the controller 14 calculates the required speed of the negative pressure centrifugal fan n=464, 370<n≤470, and the negative pressure centrifugal fan 13 reduces the gear to N3.

[0089] When the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to 0.83m, the quantitative coal discharger 3 discharges coal at a rate of 800t / h, and the controller 14 calculates the required speed of the negative pressure centrifugal fan n=368, 290<n≤370, and the negative pressure centrifugal fan 13 reduces the gear to N2.

[0090] When the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to 0.72m, the quantitative coal discharger 3 discharges coal at a rate of 800t / h, and the controller 14 calculates the required speed of the negative pressure centrifugal fan n=289, n<290, and the negative pressure centrifugal fan 13 reduces the gear to N1.

[0091] When the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to 0.5m, the quantitative coal discharger 3 reduces the coal discharge rate to 400t / h. The controller 14 calculates the required speed of the negative pressure centrifugal fan n=104, n<290, and the negative pressure centrifugal fan 13 continues to run at the N1 gear.

[0092] When the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment is reduced to within 0.2m, the quantitative coal discharger 3 reduces the coal discharge rate to 200t / h. The controller 14 calculates the required speed of the negative pressure centrifugal fan n=48, n<290, and the negative pressure centrifugal fan 13 continues to operate at the N1 gear.

[0093] Preferably, when the gear of the negative pressure centrifugal fan needs to be lowered, it is lowered step by step and the duration at each gear is not less than 3-5s. The gear is recalculated whether it needs to be further lowered until it is lowered to a suitable gear. When the gear of the negative pressure centrifugal fan needs to be raised, it is raised to the required gear at one time.

[0094] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims

1. A method for clean coal discharge in an open-pit mine, using an open-pit mine dust control device, the open-pit mine dust control device comprising a coal discharge port arranged on a floor slab, a telescopic chute arranged at the lower part of the coal discharge port, the telescopic chute comprising an inner chute and an outer chute which are hollow cylinders as a whole, the upper part of the inner chute is fixed to the coal discharge port, the inner diameter of the inner chute is consistent with the coal discharge port, the outer chute can be slidably connected to the outside of the inner chute; a dust hood is fixed to the bottom circumference of the outer chute with the outer chute as the center, one end of a hydraulic telescopic rod is connected to the upper part of the dust hood, and the other end of the hydraulic telescopic rod The vacuum hood is fixed on the floor; one end of the telescopic air duct is connected and fixed to the vacuum hood, the other end of the telescopic air duct is fixed on the floor and passes through the floor, and the end passing through the floor is connected to the flat bag dust collector through the ventilation air duct, and the flat bag dust collector is connected to the negative pressure centrifugal fan; a laser rangefinder is installed at the bottom of the vacuum hood; the vacuum hood also includes a controller, the controller is connected to the negative pressure centrifugal fan to control the working gear of the negative pressure centrifugal fan, and the controller is connected to the laser rangefinder to obtain the data measured by the laser rangefinder; the negative pressure centrifugal fan includes multiple gears, and each gear corresponds to a different fan speed; It is characterized in that The steps include: S1. The empty truck drives to the lower part of the coal discharge port, controls the hydraulic telescopic rod to extend so that the bottom of the dust hood is flush with the top surface of the truck compartment, and obtains the vertical distance L between the bottom of the dust hood and the coal discharge port; S2. The controller controls the negative pressure centrifugal fan to work, and the quantitative coal discharger starts to discharge coal to the coal discharge port at a coal discharge speed V. The laser rangefinder obtains the distance H′ between the dust hood and the coal pile in the truck compartment in real time; S3. When H′≥the short side length b of the dust hood, the negative pressure centrifugal fan operates at the highest gear; When H′<the short side length b of the dust hood, first use the following formula to calculate the required speed of the negative pressure centrifugal fan: Where n is the required negative pressure centrifugal fan speed, r / min; n max is the maximum speed of the negative pressure centrifugal fan, r / min; k is the control wind speed determination coefficient, which is 1.1; H′ is the distance between the dust hood and the coal pile in the truck compartment, m; S′ is the area of ​​the dust hood, m 2 ;Q max is the maximum air volume that the negative pressure centrifugal fan can provide when it is running, m 3 / s; η1 is the airway system efficiency, which is taken as 97%; η is the efficiency of coal pile converting work done on air into air kinetic energy, which is taken as 95%; C is the coal resistance coefficient, which is taken as 0.5; g is the acceleration of gravity, which is 9.8m / s 2 , A is the cross-sectional area of ​​the coal falling process, m 2 , V is the coal discharge rate of the coal discharge machine, t / h, V max is the maximum coal discharge rate of the coal discharge machine, t / h, A max is the cross-sectional area of ​​coal on the caving machine belt at the maximum caving rate, m 2 ; L is the vertical distance between the bottom of the dust hood and the coal discharge port, m; H is the coal drop height, m, H = H' + L; S is the cross-sectional area of ​​the coal discharge port, m 2 ; Then the controller controls the negative pressure centrifugal fan to switch to the lowest gear that satisfies the required negative pressure centrifugal fan speed n calculated by the above formula.

2. The open-pit mine clean coal discharge method according to claim 1, characterized in that: When the gear of the negative pressure centrifugal fan needs to be lowered, it is lowered step by step and maintained at each gear for a certain period of time, and then recalculated whether it is necessary to continue to lower the gear until it is lowered to a suitable gear. When the gear of the negative pressure centrifugal fan needs to be raised, it is raised to the required gear all at once.

3. Open pit mine dust control device, characterized in that: It includes the structure of the open-pit mine dust control device in claim 1, and also includes a calculation program, which is used to execute steps S1-S3 in the open-pit mine clean coal discharge method in claim 1 or 2, and the open-pit mine dust control device switches the gear of the negative pressure centrifugal fan according to the calculation program.

4. The open-pit mine dust control device according to claim 3, characterized in that: A quantitative coal placing machine is arranged on the floor slab, and the quantitative coal placing machine is connected to the bottom of the silo and the coal placing port.

5. The open-pit mine dust control device according to claim 3, characterized in that: An outward-turned boss is arranged at the bottom of the inner chute, and an inward-turned constriction is arranged at the top of the outer chute.

6. The open-pit mine dust control device according to claim 3, characterized in that: The dust hood is rectangular, with a long side consistent with the width direction of the truck compartment and a short side consistent with the traveling direction of the truck.

7. The open-pit mine dust control device according to claim 3, characterized in that: The hydraulic telescopic rods are provided with two and are symmetrically arranged on both sides of the telescopic chute; the telescopic air passages are provided with two and are symmetrically arranged on both sides of the telescopic chute.

8. The open-pit mine dust control device according to claim 3 or 7, characterized in that: The controller is connected with the hydraulic telescopic rod to control the extension and retraction of the hydraulic telescopic rod and obtain the extension and retraction length. The controller is connected with the quantitative coal placing machine to control and obtain the coal placing rate of the quantitative coal placing machine.

9. The open-pit mine dust control device according to claim 3, characterized in that: When selecting a negative pressure centrifugal fan, it should be selected according to the optimal operating point of the maximum load.

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