Coal gangue slurry preparation and conveying system and method for goaf filling

Abstract

The application discloses a coal gangue slurry preparation and conveying system and method for goaf filling, which comprises a material crushing system including a storage bin, a vibrating feeder, a multi-stage crushing system, a vibrating screen and a buffer bin; the vibrating feeder is provided with the storage bin in front and the multi-stage crushing system in back; the multi-stage crushing system comprises a plurality of crushing device systems; after being processed by a first set of crushing device systems, the material enters the vibrating screen for screening; the qualified coal gangue powder enters the buffer bin, and the unqualified material enters a second set of crushing device systems for crushing again; a stirring and slurry preparation system is used for stirring and slurry preparation of the material in the buffer bin and then feeding into a pipeline conveying system; the pipeline conveying system is provided with at least two piston pumps, which are aggregated by a shunt valve to a grouting conveying pipeline and then conveyed to a grouting area. Through the integration of the coal gangue slurry preparation and conveying, the underground filling of the goaf and the accumulation of coal-based solid waste are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gangue filling and slurry pipeline transportation, and particularly relates to a coal gangue slurry preparation and transportation system and method. BACKGROUND

[0002] Coal gangue solid waste is generated in the process of coal mining, and is one of the largest industrial solid wastes discharged in China. The coal gangue not only occupies a large amount of farmland and land, but also pollutes the surrounding soil and groundwater, and the coal gangue dust is a harmful gas that can cause serious damage to the surrounding environment. Therefore, effective treatment of coal gangue is necessary. At present, the treatment of coal gangue mainly includes crushing the coal gangue to make cement or use it as an additive of other building materials. However, the use of coal gangue is limited, and there are still limitations in relieving the pressure of coal gangue solid waste accumulation. In addition, the material is still transported by traditional transportation tools, which inevitably causes dust scattering and environmental pollution during transportation.

[0003] Slurry pipeline transportation technology is a solid-liquid mixed slurry transportation technology with water as the medium. Solid materials and water are mixed according to the required particle size gradation to prepare a solid-liquid mixed slurry with certain concentration and rheological properties. The slurry is pumped and transported to the end user through a pipeline. The slurry pipeline transportation technology is green, environmentally friendly, economical and efficient, and has been widely used in many fields such as ore transportation, deep sea mining, tailings filling and river and lake dredging. SUMMARY

[0004] The present application aims to apply the slurry pipeline transportation technology to the field of coal gangue solid waste treatment. Through a coal gangue slurry preparation and transportation system, the preparation and transportation of coal gangue slurry are integrated, and the coal gangue is applied to underground filling in the goaf. This has great significance for solving the problem of coal-based solid waste accumulation and developing new sustainable coal mining projects in the coal industry.

[0005] In view of the above defects or improvement needs of the prior art, according to the first aspect of the present application, a coal gangue slurry preparation and transportation system for goaf filling is provided, which comprises a material crushing system, a stirring and slurry preparation system and a pipeline transportation system.

[0006] The material crushing system comprises a storage bin, a vibrating feeder, a multi-stage crushing system, a vibrating screen and a buffer bin. The vibrating feeder is provided with the storage bin in front and the multi-stage crushing system in back. The multi-stage crushing system comprises a plurality of crushing device systems, a first set of crushing device systems and a second set of crushing device systems. Each crushing device system comprises at least two multi-stage crushing devices, one of which is used as a main device and the other is used as a standby device. The qualified coal gangue powder after the first set of crushing device systems is screened by the vibrating screen and enters the buffer bin, and the unqualified material enters the second set of crushing device systems.

[0007] The stirring slurry system is used to send the material in the buffer bin into the pipeline conveying system after stirring and slurry preparation;

[0008] The pipeline conveying system is provided with at least two piston pumps, one of which is used as a running pump and the other is used as a standby pump, the piston pumps are arranged below the outlet of the distribution hopper, the coal gangue slurry enters the inlet of the piston pump by gravity, a safety valve and a cleaning valve are arranged at the outlet of the piston pump, the slurry conveying pipe after the pump is provided with a discharge branch pipe, an electric valve is arranged on the discharge branch pipe, a pressure gauge is arranged on the slurry conveying pipe after the cleaning valve, and the slurry conveying pipes after each piston pump are aggregated to the grouting conveying pipeline through a flow divider.

[0009] Further, the crushing device is provided with a plurality of particle size level devices according to the required particle size of the finished coal gangue powder, and a reciprocating belt distributor can be further arranged on the top of the buffer bin, and a distribution hopper is arranged at the bottom of the buffer bin.

[0010] Further, the stirring slurry system comprises a gangue metering scale, a belt conveyor, a stirrer, a distribution hopper and a water injection system, the gangue metering scale is arranged at the bottom of the buffer bin, the material falls from the buffer bin to the gangue metering scale, is weighed and proportioned, and then enters the stirrer through the belt conveyor, the material is prepared into slurry through the stirrer, and then enters the pipeline conveying system through the distribution hopper.

[0011] Further, the water injection system comprises a mine water treatment station, a water conveying pump and a water metering scale, the clean water used for slurry preparation is pumped from the mine water treatment station through the water conveying pump, is conveyed to the water metering scale through a water conveying pipeline, and is weighed according to the set amount, and then is conveyed to the stirrer through a pipeline.

[0012] Further, the cleaning valve is further provided with an inlet through which a pipe cleaning ball enters the pipeline, and a recovery port is arranged at the outlet of the grouting conveying pipeline; the pipe cleaning ball enters the pipeline through the cleaning valve and is recovered from the reserved recovery port downstream.

[0013] Further, the safety valve and the electric valve are both connected to a pipeline branch line that is discharged into a ditch, and the electric valve is a double valve group, so that when one of the electric valves fails or needs to be repaired, the other electric valve can continue to operate.

[0014] Further, a concentration meter and a flow meter are arranged on the conveying pipeline at the outlet of the flow divider, the pipeline after the flow meter is laid according to a set slope, is buried below the permafrost layer, and finally reaches the grouting area.

[0015] According to the second aspect of the present application, a coal gangue slurry preparation and conveying method for gob filling is also provided, comprising the following steps:

[0016] a. storing the coal gangue raw material in a storage bin;

[0017] b. Feeding: uniformly feeding the coal gangue raw material in the storage bin to the multi-stage crushing system through a vibrating feeder;

[0018] c. Primary crushing: primary crushing the coal gangue raw material in the first set of crushing devices;

[0019] d. Screening: screening the primary crushed coal gangue through a vibrating screen, qualified coal gangue powder entering the buffer bin, unqualified material returning to the second set of crushing devices for secondary crushing; the secondary crushing devices and the first set of crushing devices in step c are mutually reserved to ensure the continuous operation of the multi-stage crushing system;

[0020] e. Buffering: storing the screened qualified coal gangue powder in the buffer bin;

[0021] f. Measuring: using a gangue measuring scale to quantitatively weigh the coal gangue powder in the buffer bin;

[0022] g. Transporting: transporting the weighed coal gangue powder to the mixer through a belt conveyor;

[0023] h. Treating water for slurry preparation: treating mine water in a mine water treatment station and delivering it to a water measuring scale through a water delivery pump;

[0024] i. Measuring water: using a water measuring scale to quantitatively weigh the mine water;

[0025] j. Mixing and slurry preparation: mixing the coal gangue powder and water in the mixer to prepare a slurry with a predetermined concentration. The rated capacity of the mixer in step j is 4-6 m 3 / time, and the mass concentration of the prepared slurry is 74%-75%;

[0026] k. Distributing: distributing the mixed slurry to the piston pump through a distribution hopper;

[0027] l. Transporting: using the piston pump to pressurize and transport the slurry along the pipeline to the grouting area;

[0028] m. Safety monitoring: during the transportation process, the safety valve, cleaning valve, pressure gauge, shunt valve, electric valve, concentration meter, and flow meter are used to monitor and adjust the transportation of the slurry in real time;

[0029] n. Pipeline laying: laying the pipeline after the flow meter to a predetermined slope below the permafrost layer, avoiding collision with other buildings or facilities on the ground, and reducing the need for insulation.

[0030] Further, the flow rate of the piston pump in step l is 300-340 m 3 / h, the pump pressure is 19-21 MPa, and the delivery pipeline is not less than DN200 high wear-resistant steel pipe; the safety valve in step m is arranged at the outlet of the piston pump to protect the system in case of overpressure.

[0031] Further, to reduce the possibility of clogging, the viscosity of the slurry is first estimated in step j, taking into account the effects of solid volume fraction, particle size distribution, and temperature:

[0032]

[0033] where:

[0034] η(T) is the viscosity of the slurry at temperature T, with units of Pa·S;

[0035] K(T) is a constant related to temperature T, representing the effect of temperature on the viscosity of the slurry;

[0036] C s is the solid volume fraction of the slurry, with units of %;

[0037] C s，max is the maximum solid volume fraction of the slurry, with units of %;

[0038] D avg is the average diameter of the solid particles in the slurry, with units of m;

[0039] D ref is a reference diameter, with units of m, used to standardize the effect of particle size;

[0040] n and m are experimentally determined exponents, representing the effects of solid volume fraction and particle size on viscosity, respectively;

[0041] The solid volume fraction C S is calculated using the following formula:

[0042]

[0043] where M solid is the mass of the coal gangue powder, and M total is the total mass of the coal gangue powder and water.

[0044] The particle size distribution function f(d) can be determined through sieve testing or laser particle size analysis, and then the average diameter D avg is calculated:

[0045]

[0046] The effect of temperature on the constant K(T) can be determined through experimental data, for example, the Arrhenius equation or other empirical models can be used to describe the effect of temperature on the viscosity of the slurry:

[0047]

[0048] wherein K0 is a viscosity constant at a reference temperature, E is an activation energy, R is a gas constant, and T is an absolute temperature.

[0049] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0050] 1. The coal gangue slurry preparation and conveying system for goaf filling of the present application adopts a multi-stage crushing system in cooperation with a vibrating screen, the vibrating screen screens the material treated by the multi-stage crushing system, and the oversize material with unqualified particle size is returned to the multi-stage crushing system for further classification crushing, thereby accurately controlling the particle size of the coal gangue material, effectively improving the qualified coal gangue powder output rate, ensuring that the particle size of the dry material used in the subsequent slurry preparation process meets the requirements, and further improving the system operation stability and slurry preparation quality.

[0051] 2. The coal gangue slurry preparation and conveying system for goaf filling of the present application closely combines the buffer bin with the weighing scale, temporarily stores and buffers the coal gangue material in the buffer bin, plays a role in transferring the material and balancing the material supply, and avoids flow fluctuations during material conveying; on this basis, the weighing scale accurately weighs the material output from the buffer bin in real time, accurately controls the amount of coal gangue material participating in slurry preparation in each batch, and in combination with the subsequent water weighing scale and slurry preparation process, realizes accurate batching, stably and efficiently prepares coal gangue slurry meeting the preset concentration requirements, and effectively ensures the coherence and accuracy of the entire slurry preparation process.

[0052] 3. The coal gangue slurry preparation and conveying system for goaf filling of the present application rationally sets electric valves in the system, on the one hand, considering that the solid particles in the coal gangue slurry can increase the wear rate of the valve components, a double-valve group is adopted, when the valve near the dry pipe side fails to close tightly due to wear, the other electric valve can ensure normal closing function, and when one electric valve is normally maintained, the other valve can continue to operate, thereby ensuring the normal and continuous operation of the pipe conveying system; on the other hand, since the coal gangue slurry has high pressure, manual cut-off valve operation is risky, the opening and closing time of the electric valve is controllable, and artificial operation cannot cause accelerated valve wear or pipeline vibration due to poor control of the opening degree and valve opening and closing time, and the electric valve is connected to the centralized control system, which can be opened in time when the pipeline has an abnormal working condition of overpressure, thereby avoiding pipeline pressure accumulation and pipe explosion, and improving the safety of the system. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 The process flow chart of the preferred embodiment of the present application;

[0054] Figure 2 The enlarged view of the plunger pump of the preferred embodiment of the present application;

[0055] In all the drawings, the same reference signs denote the same technical features, specifically: 1 - storage bin, 2 - vibrating feeder, 310 - first set of crushing device system, 320 - second set of crushing device system, 311 - multi-stage crushing device, 4 - vibrating screen, 5 - buffer bin, 6 - gangue metering scale, 7 - belt conveyor, 8 - mine water treatment station, 9 - water delivery pump, 10 - water metering scale, 11 - mixer, 12 - distribution hopper, 13 - piston pump, 14 - safety valve, 15 - cleaning valve, 16 - pressure gauge, 17 - flow distribution valve, 18 - electric valve, 19 - concentration meter, 20 - flow meter, 21 - slurry delivery pipe, 22 - grouting delivery pipeline, 23 - discharge branch pipe. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0057] Example 1

[0058] Please refer to Figure 1 and Figure 2 In order to achieve the above purpose, the coal gangue slurry preparation and delivery system for goaf filling provided in the present embodiment 1 comprises:

[0059] 1. Material crushing system

[0060] Storage bin 1: made of large steel structure material, with a funnel-shaped bottom design, the inner wall is lined with wear-resistant rubber plate, which not only increases the friction force to facilitate the smooth sliding of coal gangue, but also reduces the wear of the bin wall caused by the falling of the material. Its top is equipped with a dust cover and a spray dust suppression device, which can effectively suppress dust flying during feeding, and has a significant environmental protection effect; at the same time, a material level sensor is provided to accurately and real-timely monitor the coal gangue inventory in the bin, so as to facilitate timely arrangement of feeding operation.

[0061] Vibrating feeder 2: adopts electromagnetic vibration principle, and the amplitude and frequency are adjustable. Through close connection with the discharge port at the bottom of the storage bin 1, the coal gangue feeding speed can be accurately controlled to ensure that the material is uniformly and stably delivered to the subsequent multi-stage crushing system 3, avoiding equipment blockage or idling caused by uneven feeding.

[0062] Multi-stage crushing system: composed of two sets of crushing device systems, each set containing two multi-stage crushing devices 311. The multi-stage crushing device 311 of the first set of crushing device system 310 is preferably a combination of a jaw crusher and an impact crusher. The jaw crusher is responsible for coarse crushing, rapidly reducing the particle size of large coal gangue from >30mm to 3-30mm, and the impact crusher performs medium and fine crushing. The second set of crushing device system 320 is equipped with a cone crusher as a backup and fine processing unit. When the particle size of the material after the first set of processing is still unqualified >3mm, the cone crusher can accurately crush it to the target particle size with high crushing ratio. Each set of system has a backup for each crusher. Through intelligent electric control system, it can automatically switch in the event of main equipment failure, ensuring production continuity, and the equipment is connected by airtight belt conveyor, reducing material scattering and dust emission.

[0063] Vibrating screen 4: high-frequency vibrating screen with a mesh size of 3mm and a screening efficiency of over 95%. The screen body is supported by high-strength springs and driven by a vibrating motor, which can quickly and accurately classify the crushed material. The qualified coal gangue powder <3mm is directly dropped into the buffer bin 5 through the chute, and the unqualified material is automatically sent back to the second set of crushing device system 320 for reprocessing.

[0064] Buffer bin 5: The top of the bin is equipped with a rotatable material scraper to ensure uniform distribution of coal gangue powder and prevent compaction. The bottom of the bin is funnel-shaped and equipped with an electric material gathering door, which seamlessly connects with the gangue weighing scale 6, accurately controls the discharge amount, and ensures the uniformity of the subsequent batching process.

[0065] 2. Stirring and slurry preparation system

[0066] Gangue weighing scale 6: high-precision electronic belt scale that dynamically weighs the coal gangue powder output from the buffer bin 5 in real time. The weighing data is transmitted to the central control system in real time to accurately control the feed amount according to the set formula. The scale body surface is specially hardened to resist wear and corrosion, extending the service life.

[0067] Belt conveyor 7: uses a rubber conveyor belt with anti-slip patterns on the surface, and protective baffles and cleaning devices are installed on both sides of the machine body to stably and efficiently convey the coal gangue powder weighed by the gangue weighing scale 6 to the mixer 11 without any spillage.

[0068] Mixer 11: selects a double-shaft forced mixer with a rated capacity of 5m 3 / minute to produce a slurry with a mass concentration of 74%-75% and a slurry stiffness coefficient of 395.55-522.18mPa·S. The stirring paddle is designed in a unique spiral shape and made of high-chromium alloy, which is wear-resistant and has excellent stirring effect. The machine casing is lined with polyurethane wear-resistant plates to reduce material impact and wear. It is equipped with a variable frequency motor that can flexibly adjust the stirring speed according to the material characteristics and concentration requirements, achieving rapid and uniform mixing of coal gangue powder and water.

[0069] Distribution hopper 12: The conical hopper is made of stainless steel, with smooth inner wall. The bottom is provided with an electric gate valve and a flow regulating valve to precisely control the flow direction and flow rate of the slurry, so as to ensure the stable entry of the slurry into the piston pump 13 and avoid blockage and overflow. A liquid level sensor is arranged on the outer side of the hopper body to monitor the slurry liquid level in real time, and the automatic control is realized in linkage with the central control system.

[0070] Water injection system: The mine water treatment station 8 is provided with multiple purification processes such as sedimentation, filtration and reverse osmosis to ensure the water quality is pure and free of impurities, and meet the standard of water for pulp making. The water delivery pump 9 is a centrifugal pump, which stably delivers the purified water to the water metering scale 10. The water metering scale 10 has the same accuracy standard as the gangue metering scale 6, and accurately measures the water according to the formula, which is accurately injected into the mixer 11 through the pipeline, flow meter and regulating valve.

[0071] 3. Pipeline delivery system

[0072] Piston pump 13: At least two high-power piston pumps (one main and one backup) are provided. The main pump has a flow rate of 320 m 3 / h, a pump pressure of 20 MPa, and the backup pump is the same as the main pump. The pump body is made of high-strength alloy casting, and the piston is a ceramic-coated piston, which is wear-resistant and corrosion-resistant. A filter with a filtering accuracy of 3 mm is arranged at the inlet of the pump to prevent large particles of coal gangue from entering the pump body and damaging the components. The outlet of the pump is connected to the slurry delivery pipe by flange, which is reliable in sealing. Two piston pumps 13 are provided with a discharge branch pipe after the pumps. When the pump is stopped for maintenance or accident, water is injected through the water injection pipe on the piston pump 13 to flush the pipeline, so as to prevent the residual slurry from blocking the pipeline. The waste slurry after flushing is discharged into a ditch through the discharge branch pipe.

[0073] Safety valve 14: installed at the outlet of the piston pump 13, which is a spring safety valve with rapid response and instant opening when the pressure is too high. The discharged slurry is safely discharged into a ditch through the pipeline branch. The valve body is made of stainless steel, which is resistant to high pressure and erosion. Regular calibration ensures reliable performance. The piston pump 13 has high output pressure, which is suitable for short-distance delivery of coarse particles, high concentration and high viscosity slurry, and can meet the pipeline delivery requirements of coal gangue slurry. The piston pump 13 is provided with an overpressure alarm and cut-off device to protect the safety of the pump equipment and the upstream process system. However, the safety of the downstream pipeline delivery system cannot be guaranteed. The safety valve 14 at the outlet of the piston pump 13 is arranged to deal with this overpressure abnormal condition and ensure the safety of the pipeline delivery system.

[0074] Cleaning valve 15: a ball valve structure, which has the functions of cutting off the slurry delivery pipe at the pump outlet and cleaning the pipeline system. The cleaning ball is slightly smaller in diameter than the inner diameter of the pipeline, and is made of polyurethane, which is elastic and wear-resistant. A cleaning ball recovery port is arranged at the outlet of the pipeline in the grouting area, and a guide device is arranged on the pipeline to ensure the smooth operation and recovery of the cleaning ball. Regular cleaning can maintain the cleanliness of the inner wall of the pipeline and reduce the delivery resistance.

[0075] Pressure gauge 16: clear dial, accurate reading, real-time monitoring of pump outlet and pipeline pressure, data transmission to the central control system, convenient for operators to master the pressure dynamics in time and adjust the equipment operating parameters; the gauge body has a protective cover, anti-shock and pressure-resistant, suitable for complex working conditions.

[0076] Split valve 17: electric three-way split valve is selected, which can remotely control the slurry split ratio, switch flexibly and has good sealing performance; it is tightly connected with the slurry conveying pipe after the running pump and standby pump, and the polymer slurry is sent to the grouting conveying pipeline to ensure the continuity and stability of the conveying. When the plunger pump 13 switches between running pump and standby pump, the split valve 17 realizes the rapid switching of the working flow channel, improves the conveying efficiency, reduces the number of elbow pipes and the length of the pipeline, optimizes the pipeline layout, and prevents pipe blockage.

[0077] Electric valve 18: double valve group is adopted, both are electric ball valves, single valve diameter DN200, switch time <5s; the solid particles in the coal gangue slurry can increase the wear rate of the valve parts, by setting electric valve 18 double valve group on the discharge branch pipe, the wear rate of the valve near the dry pipe side is faster, when it fails to close tightly due to wear, etc., the other electric valve 18 can ensure normal closing function, at the same time, when one of the electric valves 18 is normally maintained, the other valve can continue to operate to ensure the normal and continuous operation of the pipeline system; the coal gangue slurry has high pressure, manual cut-off valve has certain operation risk, and if the opening degree and valve opening and closing time are not grasped well during manual operation, it will accelerate the wear of the valve, or cause pipeline vibration, the use of electric valve 18 is safer, and the opening and closing time of the valve is controllable, which avoids abnormal working conditions caused by too fast or too slow opening and closing of the valve; pressure gauge 16 and electric valve 18 are connected to the centralized control system, when the pipeline appears overpressure abnormal condition, the electric valve 18 can be opened in time to avoid the pressure of the pipeline, ensure the safety of the pipeline conveying system.

[0078] Concentration meter 19: online ultrasonic concentration meter is selected, which can monitor the solid content of the slurry in real time, and feedback the data to the central control system in real time, so as to adjust the proportioning in the slurry preparation link in time according to the concentration fluctuation to ensure the stability of the slurry quality.

[0079] Flow meter 20: electromagnetic flow meter is adopted, which can accurately measure the slurry flow to provide key data for the speed regulation of the plunger pump 13 and system capacity calculation; the flow meter is installed in the horizontal straight pipe section, and enough straight pipe length is reserved in front and back to ensure accurate measurement; the data is connected to the central control system to realize visual monitoring and control of the flow. The pipeline after the flow meter 20 is laid according to the laying angle determined by the experiment and slopes to the underground below the permafrost layer. The pipeline is buried to avoid collision with other buildings or facilities on the ground. At the same time, the pipeline is below the permafrost layer and does not need to be insulated.

[0080] Example 2

[0081] In order to achieve the above-mentioned purpose, the coal gangue slurry preparation and conveying method for goaf filling provided by the embodiment 2 comprises:

[0082] The material preparation and crushing process: the coal gangue raw material is transported to the storage bin 1 by the mine area transport vehicle, and the spray dust suppression device is opened when unloading to suppress dust; the material is fed in time according to the data of the material level sensor. The vibrating feeder 2 is started, the feeding speed is set according to the production plan, and the coal gangue falls uniformly into the first set of crushing device system 310. In the coarse crushing stage, the jaw crusher rapidly crushes the coal gangue with a particle size of >30 mm to 3-30 mm; in the medium and fine crushing stage, the impact crusher reduces the particle size of the material to below 3 mm, and the crushed material is sent to the vibrating screen 4 by the belt conveyor. The qualified coal gangue powder with a particle size of <3 mm falls into the buffer bin 5; the unqualified material on the screen is automatically transported to the second set of crushing device system 320 by the return belt, and the cone crusher accurately crushes it for the second time until the particle size meets the standard. The whole process is cooperated by the devices according to the instructions of the central control system, so as to ensure the high efficiency and stability of the crushing process.

[0083] The stirring and slurry preparation operation steps: the electric material door at the bottom of the buffer bin 5 is opened according to the set amount, and the coal gangue powder falls into the coal gangue scale 6. After the coal gangue powder is accurately weighed by the scale body, it is conveyed to the stirrer 11 by the belt conveyor 7; at the same time, the purified water in the mine water treatment station 8 is pumped by the water pump 9, and the water scale 10 takes the weight of the water corresponding to the weight of the coal gangue powder, and the water is injected into the stirrer 11 through the pipeline and the regulating valve.

[0084] In order to reduce the possibility of blockage, the viscosity is estimated before slurry preparation, considering the influence of solid volume fraction, particle size distribution and temperature:

[0085]

[0086] Wherein:

[0087] η(T) is the viscosity of the slurry at temperature T, with the unit of Pa·S;

[0088] K(T) is a constant related to temperature T, representing the influence of temperature on the viscosity of the slurry;

[0089] C S is the solid volume fraction of the slurry, with the unit of %;

[0090] C S，max is the maximum solid volume fraction of the slurry, with the unit of %;

[0091] D avg is the average diameter of the solid particles in the slurry, with the unit of m;

[0092] D ref is a reference diameter, with the unit of m, used to standardize the influence of particle size;

[0093] n and m are experimentally determined indices representing the effect of solid volume fraction and particle size on viscosity, respectively;

[0094] Volume fraction C S , using the following formula:

[0095]

[0096] where M solid is the mass of coal gangue powder, M total is the total mass of coal gangue powder and water.

[0097] The particle size distribution function f(d) can be determined by sieving experiments or laser particle size analysis, and then the average diameter D avg is calculated:

[0098]

[0099] The effect of temperature on the constant K(T) can be determined by experimental data, for example, the Arrhenius equation or other empirical models can be used to describe the effect of temperature on the viscosity of the slurry:

[0100]

[0101] where K0 is the viscosity constant at a reference temperature, E is the activation energy, R is the gas constant, and T is the absolute temperature.

[0102] If the estimated viscosity is too large, it is easy to cause blockage, and various parameters of the system operation can be adjusted to reduce the viscosity.

[0103] After the coal gangue powder and the water required for pulping enter the mixer, the mixer 11 is started, and the material is preliminarily mixed at low speed for 5 minutes, and then adjusted to high speed for 15 minutes to produce a slurry with a mass concentration of 75%. The slurry is controlled by the electric gate valve at the bottom of the distribution hopper 12 and the flow regulating valve, and smoothly flows into the piston pump 13. The parameters of the ingredients and stirring in each link are precisely controlled by the central control system according to the preset process, to ensure that the quality of the slurry meets the standards.

[0104] The pipeline conveying operation mode: the plunger pump 13 main pump is started, and the slurry is advanced along the pipeline under the action of pump pressure. The pump outlet pressure is monitored in real time by the pressure gauge 16. The safety valve 14 is in standby state, and is quickly opened to release when the pressure is too high. During operation, the cleaning valve 15 is opened periodically every month to put in the cleaning ball to clean the coal gangue attached to the inner wall of the pipeline, and the cleaning ball is taken out from the downstream recovery port. The electric valve 18 is automatically controlled according to the system pressure and flow, and when one side valve fails, the other valve can be seamlessly switched to ensure the smoothness of the pipeline. The shunt valve 17 flexibly adjusts the slurry shunt ratio according to the working condition, and the slurry after the operation pump and the standby pump is stably aggregated to the grouting conveying pipeline. The concentration meter 19 and the flow meter 20 monitor the slurry concentration and flow in real time, and the data is fed back to the central control system. The operator adjusts the plunger pump 13 speed, valve opening and other parameters accordingly to ensure that the slurry is stably and accurately delivered to the goaf grouting area along the pipeline laid below the permafrost layer. The whole process is intelligently and finely controlled to realize efficient and safe conveying.

[0105] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A coal gangue slurry preparation and delivery system for gob filling, characterized in that, The application relates to a coal gangue powder preparation system. The coal gangue powder preparation system comprises a material crushing system, a stirring and slurry preparation system and a pipeline conveying system. The material crushing system comprises a storage bin (1), a vibrating feeder (2), a multi-stage crushing system, a vibrating screen (4) and a buffer bin (5); the vibrating feeder (2) is arranged in front of the storage bin (1) and behind the multi-stage crushing system; the multi-stage crushing system comprises a plurality of crushing device systems, a first crushing device system (310) and a second crushing device system (320); each crushing device system comprises at least two multi-stage crushing devices (311); after being treated by the first crushing device system (310), the material enters the vibrating screen (4); the qualified coal gangue powder after screening enters the buffer bin (5); and the unqualified material enters the second crushing device system (320). The stirring and slurry preparation system is used for stirring and slurry preparation of the material in the buffer bin (5) and then feeding the material into the pipeline conveying system. The pipeline conveying system is provided with at least two plunger pumps (13); the plunger pumps (13) are arranged below the outlets of the distribution hoppers (12); the coal gangue slurry enters the inlets of the plunger pumps (13) through gravity; safety valves (14) and cleaning valves (15) are arranged at the outlets of the plunger pumps (13); the slurry conveying pipes after the plunger pumps (13) are provided with discharging branch pipes; electric valves (18) are arranged on the discharging branch pipes; pressure gauges (16) are arranged on the slurry conveying pipes after the cleaning valves (15); and the slurry conveying pipes (21) after each plunger pump are aggregated into a grouting conveying pipeline (22) through a flow divider (17). The multi-stage crushing devices (311) of the first crushing device system (310) are combined by jaw crushers and impact crushers; the jaw crushers are responsible for coarse crushing; and the impact crushers are responsible for medium and fine crushing. The second crushing device system (320) is provided with a cone crusher as a backup and fine processing unit; when the particle size of the material after the first processing is still unqualified (greater than 3 mm), the cone crusher breaks the material to the target particle size through a high crushing ratio.

2. The coal gangue slurry preparation and delivery system for goaf filling according to claim 1, characterized in that: The crushing devices (311) are provided with a plurality of particle size level devices according to the required particle size of the finished coal gangue powder; a reciprocating belt distributor can also be arranged on the top of the buffer bin (5); and a distribution hopper is arranged at the bottom of the buffer bin (5).

3. The coal gangue slurry preparation and delivery system for goaf filling according to claim 1, characterized in that: The stirring and slurry preparation system comprises a coal gangue metering scale (6), a belt conveyor (7), a stirrer (11), a distribution hopper (12) and a water injection system; the coal gangue metering scale (6) is arranged at the bottom of the buffer bin (5); the material falls from the buffer bin (5) to the coal gangue metering scale (6), is weighed and proportioned, then enters the stirrer (11) through the belt conveyor (7); and the material is slurry-prepared in the stirrer (11) and then enters the pipeline conveying system through the distribution hopper (12).

4. The coal gangue slurry preparation and delivery system for goaf filling according to claim 3, characterized in that: The water injection system comprises a mine water treatment station (8), a water conveying pump (9) and a water metering scale (10); the clean water for slurry preparation is pumped from the mine water treatment station (8) by the water conveying pump (9), is conveyed to the water metering scale (10) through a water conveying pipeline, is weighed according to the set quantity, and then is conveyed into the stirrer (11) through a pipeline.

5. The coal gangue slurry preparation and delivery system for goaf filling according to claim 1, characterized in that: The cleaning valve (15) is also provided with an inlet of pig entering pipeline, and a recovery port is arranged at the outlet of the grouting pipeline (22); the pig enters the pipeline through the cleaning valve (15) and is recovered from the reserved recovery port downstream.

6. The coal gangue slurry preparation and delivery system for goaf filling according to claim 1, characterized in that: The safety valve (14) and the electric valve (18) are both connected with pipeline branches discharging into a ditch; and the electric valve (18) is a double valve group, when one of the electric valves (18) fails or is under maintenance, the other electric valve (18) can continue to operate.

7. A coal gangue slurry preparation and delivery system for gob filling according to any one of claims 1-6, characterized in that: A concentration meter (19) and a flow meter (20) are arranged on the grouting pipeline (22) at the outlet of the shunt valve (17); the pipeline after the flow meter (20) is laid according to a set slope, is buried below the permafrost layer, and finally reaches the grouting area.

8. A coal gangue slurry preparation and delivery method for a coal gangue slurry preparation and delivery system for gob filling, which is applied to the coal gangue slurry preparation and delivery system for gob filling according to claim 7, characterized in that, The method comprises the following steps: a. storing the coal gangue raw materials in a storage bin (1); b. feeding: uniformly feeding the coal gangue raw materials in the storage bin (1) to a multi-stage crushing system (3) through a vibrating feeder (2); c. primary crushing: primary crushing the coal gangue raw materials in a first set of crushing devices; d. screening: screening the primary crushed coal gangue through a vibrating screen (4), qualified coal gangue powder enters a buffer bin (5), and unqualified materials return to a second set of crushing devices for secondary crushing; the second set of crushing devices and the first set of crushing devices in step c are used alternately to ensure continuous operation of the multi-stage crushing system; e. buffering: storing the screened qualified coal gangue powder in the buffer bin (5); f. metering: quantitatively weighing the coal gangue powder in the buffer bin (5) using a gangue metering scale (6); g. conveying: conveying the weighed coal gangue powder to a mixer (11) through a belt conveyor (7); h. treating water for slurry preparation: treating mine water in a mine water treatment station (8) and conveying the mine water to a water metering scale (10) through a water conveying pump (9); i. water metering: quantitatively weighing the mine water using the water metering scale (10); j. mixing and slurry preparation: mixing the coal gangue powder and the water in the mixer (11) to prepare slurry of a predetermined concentration; the rated capacity of the mixer (11) is 4-6 m³ / time, and the mass concentration of the prepared slurry is 74%-75%; k. distributing: distributing the mixed slurry to a plunger pump (13) through a distributing hopper (12); l. conveying: conveying the slurry along a pipeline to a grouting area by pressurizing the slurry using the plunger pump (13); m. safety monitoring: monitoring and adjusting the conveying of the slurry in real time by the safety valve (14), the cleaning valve (15), the pressure gauge (16), the shunt valve (17), the electric valve (18), the concentration meter (19), and the flow meter (20); n. pipeline laying: laying the pipeline after the flow meter (20) to below the permafrost layer according to a predetermined slope, to avoid collision with other buildings or facilities on the ground and to reduce the need for thermal insulation; The viscosity of the slurry is estimated in step j, considering the influence of the solid volume fraction, the particle size distribution, and the temperature: wherein: is the viscosity of the slurry at temperature T, in units of ; is a constant related to temperature T, representing the influence of temperature on the viscosity of the slurry; is the solids volume fraction of the slurry in %; is the maximum solids volume fraction of the slurry in %; is the average diameter of the solid particles in the slurry, in m; is a reference diameter in m that normalizes the effect of particle size; n and m are experimentally determined exponents, respectively representing the influence of the solid volume fraction and the particle size on the viscosity. volume fraction Using the following equation: wherein, is the mass of coal gangue powder, is the total mass of coal gangue powder and water; Calculating the average diameter : Particle size distribution function Determined by screening tests or laser particle size analysis, then temperature versus constant. The effect of temperature on slurry viscosity is determined through experimental data, using the Arrhenius equation or other empirical models to describe the influence of temperature: wherein, is the viscosity constant at the reference temperature, E is the activation energy, R is the gas constant, and T is the absolute temperature.

9. A coal gangue slurry preparation and delivery method for goaf filling according to claim 8, characterized in that: The flow rate of the plunger pump (13) in step l is a value between 300-340 m³ / h, the pump pressure is between 19-21 MPa, and the delivery pipeline is a high-wear-resistance steel pipe with a specification no less than DN200; the safety valve (14) in step m is arranged at the outlet of the plunger pump (13) and is used for protecting the system safety in the case of overpressure.

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