Open pit mine dust control device and clean coal caving method

Abstract

The present invention belongs to the field of dust prevention and removal devices and methods for open-pit mines, and specifically relates to a dust control device and a clean coal discharge method for open-pit mines. The open-pit mine dust control device includes a coal discharge port arranged on a floor slab, a telescopic chute is arranged at the lower part of the coal discharge port, the upper part of the telescopic chute is fixed to the coal discharge port, and a dust hood is fixed circumferentially at the lower part. A hydraulic telescopic rod and a telescopic air duct are arranged between the dust hood and the floor slab, the ventilation air duct passing through the end of the floor slab is connected to a flat bag dust collector, the flat bag dust collector is connected to a negative pressure centrifugal fan, and a laser rangefinder is installed at the bottom of the dust hood; the clean coal discharge method can adjust 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. The present invention can achieve efficient and energy-saving control of dust pollution at the coal discharge port.

Description

Technical Field

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

[0002] Coal is an important energy source. Coal production and transportation systems involve numerous transfer processes, which generate significant amounts of dust. Loading coal into open-pit mines generates significant amounts of dust, severely polluting the surrounding environment and endangering worker health.

[0003] At present, the existing chute equipment cannot adjust the distance between the chute and the carriage. The area of ​​the chute not covered by the dust hood 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 on-site dust conditions, resulting in waste of electricity or causing large dust problems. Summary of the Invention

[0004] In response to the above technical problems, the present invention proposes an open-pit mine dust control device and a clean coal discharge method. It 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, which can achieve 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 on the bottom circumference of the outer chute with the outer chute as the center, and 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. One end of the telescopic air duct is fixed to the passage, and the other end of the telescopic air duct is fixed to 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, which 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 provided 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 traveling direction of the truck.

[0009] Preferably, two hydraulic telescopic rods are provided, symmetrically arranged on both sides of the telescopic chute, and two telescopic air ducts 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 caving machine to control and obtain the coal caving rate of the quantitative coal caving 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 caving method adopts the open-pit mine dust control device described above, and includes the following steps:

[0013] S1. Drive an empty truck to the bottom of the coal discharge port. Extend the hydraulic telescopic rod so that the bottom of the dust hood is flush with the top of the truck compartment. Measure 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 operate, and the quantitative coal discharger begins to discharge coal into the coal discharge port at a discharge speed V. The laser rangefinder obtains the distance H′ between the dust collection hood and the coal pile in the truck compartment in real time.

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

[0016] When H' is less than 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 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, which is taken as 97%; η is the efficiency of the coal pile in 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 due to 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 then 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 coal loading operations on trucks of various sizes. The extension length of the telescopic chute is adjusted to the truck size, separating the falling coal from the working space, greatly reducing the impact of the entrained airflow on the coal, and thus effectively reducing the dust generated by the coal loading operation;

[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 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 diagrams of the silo loading station of the present invention in front and side views;

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

[0027] Figure 3 This is a schematic diagram of the inner chute and outer chute structures 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 Schematic diagram of wind speed control according to 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 column just below the coal discharge port 19, pile 20, and dust source 21. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] Example 1

[0033] like Figure 1-3 As shown, the open-pit mine dust control device includes a coal discharge port 4 provided on the floor slab, and a quantitative coal discharger 3 is provided on the floor slab. 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 cylindrical bodies. The upper part of the inner chute 6 is fixed to the coal discharge port. The inner diameter of the inner chute 6 is consistent with that of 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, and 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. The upper part of the dust hood 9 is connected to one end of a hydraulic telescopic rod 5, 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 chute and length change; the dust hood 9 is connected to 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 is preferably rectangular. When rectangular, the long side is consistent with the width of the truck compartment, and the short side is consistent with the direction of travel of the truck, that is, the length of the truck compartment; two hydraulic telescopic rods 5 are provided, symmetrically arranged on both sides of the telescopic chute, and two telescopic air ducts 10 are provided, 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] The controller 14 is further comprised of a controller 14 connected to the negative pressure centrifugal fan 13 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 and retraction length, the controller 14 is connected to the quantitative coal caving machine 3 to control and obtain the coal caving rate of the quantitative coal caving machine 3, and the controller 14 is connected to the laser rangefinder 8 to obtain 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] Example 2

[0039] The open-pit mine clean coal caving method adopts the open-pit mine dust control device of the first embodiment, and includes the following steps:

[0040] S1. An unloaded truck 2 moves to the lower portion of the coal discharge port 4. 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 based on the original length and the telescopic length of the hydraulic telescopic rod.

[0041] S2. The controller 14 controls the negative pressure centrifugal fan 13 to start coal discharge. Coal is discharged from the bottom of the silo 1 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 speed V. During the coal discharge process, the laser rangefinder 8 obtains the distance H' between the dust collection 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′ is less than 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 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 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, which is about 97%; η is the efficiency of the coal pile in 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 due to 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 ;

[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, which correspond 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 Example 2 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 it experiences 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 height of coal falling, m, H=H′+L, g is the acceleration due to gravity, 9.8m / s 2 ; ρ is the air density, kg / m 3 .

[0052] Since the inner diameter of the inner chute 6 is not much different from that 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 considered, that is, 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 fact that the action force and reaction force are the same, the work W done by the coal on the air during the falling process can be 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 in the column 19 just 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 so that the dust moves 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] Where, v x is the controlled wind speed, m / s; k is the control wind speed determination coefficient, which is 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 formula (7), formula (8) and formula (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] Where 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 negative pressure centrifugal fans:

[0075]

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

[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 the negative pressure centrifugal fan, m 3 / s.

[0079] Example 3

[0080] The open-pit mine dust control device is as described in Example 1. In addition, the control device also includes a calculation program, which is used to execute the method in Example 2. The control device switches the gear of the negative pressure centrifugal fan according to the calculation program.

[0081] Example 4

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

[0083] The coal discharge rate of the quantitative coal discharger 3 is 0-800t / h, that is, the maximum coal discharge rate of the quantitative coal discharger 3 is V max The belt width of the quantitative coal caving machine 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 caving machine 3 at the maximum coal caving 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 bottom surface of the dust cover 9 is rectangular in shape, with a long side a of 1.5m and a short side b of 1.3m. Its area S' is 1.95m2 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. The performance parameters of the 4-79-16e centrifugal fan are the maximum speed n max The maximum air volume is 740r / min, Q 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 the 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 2. At this time, the coal falling height H is 3.6m.

[0085] The controller 14 controls the negative pressure centrifugal fan 13 to start coal discharge. The coal is discharged from the bottom 1 of the silo to the quantitative coal discharger 3. The quantitative coal discharger 3 discharges the coal from the coal discharge port 4 and the telescopic chute into 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 coal pile 20 is greater than 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 operation progresses, when the distance H′ between the dust hood 9 and the coal pile 20 in the truck compartment decreases to 1.3 m, the quantitative coal discharger 3 discharges coal at a rate of 800 t / h. The controller 14 calculates the required speed of the negative pressure centrifugal fan n=890, n>580, and the negative pressure centrifugal fan 13 continues to operate 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. 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. 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. 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. 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 operate 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] Those skilled in the art can make various corresponding changes and modifications based on the above technical solutions and concepts, and all of these changes and modifications should be included in the scope of protection of the claims of the present invention.

Claims

1. A clean coal discharge method for 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 portion 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 portion of the inner chute being fixed to the coal discharge port, the inner diameter of the inner chute being consistent with the coal discharge port, the outer chute being 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, the upper portion of the dust hood is connected to one end of a hydraulic telescopic rod, the other end of the hydraulic telescopic rod The hood is fixed to the floor; one end of a telescopic air duct is connected and fixed to the hood, the other end of which is fixed to the floor and passes through the hood, and the end that passes through the floor is connected to a flat bag dust collector via 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 hood; the hood also includes a controller, which 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 data measured by the laser rangefinder; the negative pressure centrifugal fan has multiple gears, each gear corresponding to a different fan speed; It is characterized by: The steps include: S1. Drive an empty truck to the bottom of the coal discharge port. Extend the hydraulic telescopic rod so that the bottom of the dust hood is flush with the top of the truck compartment. Measure 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 operate, and the quantitative coal discharger begins to discharge coal into the coal discharge port at a discharge speed V. The laser rangefinder obtains the distance H′ between the dust collection hood and the coal pile in the truck compartment in real time. S3. When H′ ≥ b, the length of the short side of the dust hood, the negative pressure centrifugal fan operates at the highest gear; When H' is less than 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 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, which is taken as 97%; η is the efficiency of the coal pile in 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 due to 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 caving 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 time, and then recalculated whether the gear needs to be further lowered until it is lowered to the appropriate gear. When the gear of the negative pressure centrifugal fan needs to be raised, it is raised to the required gear at one time.

3. Open pit mine dust control device, characterized in that, It includes the open-pit mine dust control device structure of claim 1, and also includes a calculation program, which is used to execute steps S1-S3 in the open-pit mine clean coal caving method according to 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 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 provided at the bottom of the inner chute, and an inward-turned constriction is provided 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 its long side consistent with the width direction of the truck compartment and its 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: There are two hydraulic telescopic rods, which are symmetrically arranged on both sides of the telescopic chute; there are two telescopic air ducts, which 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 to the hydraulic telescopic rod to control the extension and contraction of the hydraulic telescopic rod and obtain the extension and contraction length. The controller is connected to the quantitative coal caving machine to control and obtain the coal caving rate of the quantitative coal caving machine.

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

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