A closed cycle air jet milling system for milling materials

Abstract

This invention discloses a closed-loop circulating airflow pulverizing system for material pulverization, including a material path pipeline and an air path pipeline. The air path pipeline includes a pulverizing air path and a regulating air path. The pulverizing air path is as follows: a first air supply system is divided into two paths via a gas distributor; one path supplies the feed nozzle of the airflow pulverizer, and the other path supplies the pulverizing chamber of the airflow pulverizer. The pulverizing chamber of the airflow pulverizer is connected to the outer cavity of a bag filter installed inside a material collector. A second air supply system is connected to the first air port of a balance tank via a constant-speed nitrogen replenishment valve and a fifth control valve. The second air supply system is also connected to the first air port of the balance tank via a low-pressure nitrogen replenishment valve and a fast nitrogen replenishment valve. The fifth air port of the material collector, which is connected to the inner cavity of the bag filter, is connected to the first air port of the balance tank via the first control valve. The closed-loop structure effectively prevents easily oxidized and moisture-absorbing materials such as lithium battery materials and pharmaceutical raw materials from deteriorating or deteriorating during pulverization.

Description

Technical Field

[0001] This invention relates to the field of material crushing and processing equipment, specifically to a closed-loop circulating airflow crushing system for material crushing, which is particularly suitable for crushing and processing easily oxidized and moisture-absorbing materials such as lithium battery solid electrolytes and pharmaceutical raw materials. Background Technology

[0002] Airflow milling technology pulverizes materials by using airflow to cause particles to collide and rub against each other. It boasts advantages such as high pulverization efficiency, uniform particle size, and low pollution, and is widely used in chemical, pharmaceutical, and new materials industries. However, for certain materials, such as lithium-ion battery cathode materials, rare earth functional materials, and precision ceramics, which are prone to oxidation and moisture absorption, the moisture and oxygen content in the pulverization system must be controlled during the pulverization process; otherwise, the materials may oxidize, deteriorate, or experience performance degradation.

[0003] Existing airflow milling equipment typically employs simple nitrogen protection measures, which have the following technical drawbacks: 1. The feeding process cannot be completely sealed, easily introducing external moisture and oxygen; 2. Large pressure fluctuations occur during material collection, leading to backflow of external gases; 3. The gas replenishment method is singular, unable to simultaneously address both steady-state pressure stabilization and instantaneous pressure compensation, resulting in poor operational stability. These problems severely restrict the application of airflow milling technology in the processing of easily oxidized and hygroscopic materials. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a closed-loop circulating airflow pulverizing system for material pulverization.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a closed-loop circulating airflow pulverizing system for material pulverization, including a material path pipeline and an air path pipeline; the air path pipeline includes a pulverizing air path and a regulating air path;

[0006] The material pipeline is as follows: the material is fed into the air jet mill for crushing via the feeding device, and then discharged from the material collector after gas-solid separation.

[0007] The pulverizing air path is as follows: the first air supply system is divided into two paths by a gas distributor. One path supplies the feed nozzle of the air jet pulverizer, and the other path supplies the pulverizing chamber of the air jet pulverizer. The pulverizing chamber of the air jet pulverizer is connected to the outer cavity of the bag filter installed in the material collector.

[0008] The regulating gas path includes a balance tank, a constant-speed nitrogen replenishment valve, a low-pressure nitrogen replenishment valve, and a rapid nitrogen replenishment valve. The second gas supply system is connected to the first gas port of the balance tank through the constant-speed nitrogen replenishment valve and the fifth control valve. The second gas supply system is connected to the first gas port of the balance tank through the low-pressure nitrogen replenishment valve and the rapid nitrogen replenishment valve. The fifth gas port of the material collector, which is connected to the inner cavity of the bag filter, is connected to the first gas port of the balance tank through the first control valve.

[0009] The second air port of the balance tank is connected to the sixth air port of the air storage tank in the first air supply system via the air compressor and the second control valve.

[0010] Preferably, the seventh gas port of the gas storage tank is connected to the gas distributor via a refrigerated dryer, a desiccant dryer, and a gas buffer tank. The gas distributor is connected to the feed nozzle of the air jet mill via a third control valve. The gas distributor is connected to the grinding chamber of the air jet mill via a fourth control valve.

[0011] Preferably, a shut-off valve and a check valve are connected between the second air port of the balance tank and the second control valve; the second air port of the balance tank is located above the first air port of the balance tank.

[0012] Preferably, a first pressure gauge is installed on the pipeline between the first air port of the balance tank and the fifth air port of the material collector;

[0013] The opening condition of the low-pressure nitrogen replenishment valve is as follows: when the real-time pressure measured by the first pressure test gauge is less than the set working positive pressure threshold, the valve is opened and the second gas supply system replenishes nitrogen into the balance tank through the opened low-pressure nitrogen replenishment valve to increase the gas pressure in the regulating gas path.

[0014] The closing condition of the low-pressure nitrogen replenishment valve is: it closes when the real-time pressure measured by the first pressure test gauge after replenishment is greater than or equal to the working positive pressure threshold.

[0015] Preferably, a second pressure gauge is installed on the pipeline from the gas distributor to the grinding chamber of the airflow pulverizer;

[0016] When the real-time pressure measured by the second pressure gauge is lower than the set lower limit threshold of the working positive pressure, the constant-speed nitrogen replenishment valve opens, and the second gas supply system replenishes nitrogen into the balance tank through the opened constant-speed nitrogen replenishment valve and the fifth control valve.

[0017] The constant-speed nitrogen replenishment valve closes when the real-time pressure measured by the second pressure test gauge rises back to the set upper limit threshold of the working positive pressure after the gas replenishment.

[0018] Preferably, the rapid nitrogen replenishment valve is used for instantaneous pressure compensation during material discharge.

[0019] The material collector is equipped with a double discharge valve below it; the double discharge valve includes a first gate valve and a second gate valve connected in series; the discharge process is as follows: the first gate valve opens, and the material falls into the temporary storage cavity between the first gate valve and the second gate valve; after the first gate valve closes, the second gate valve opens, allowing the material to be discharged from the temporary storage cavity;

[0020] The opening conditions for the rapid nitrogen replenishment valve are as follows:

[0021] The rapid nitrogen replenishment valve opens 0.3 to 0.5 seconds before the first gate valve opens, replenishing the balance tank with gas.

[0022] The closing condition of the rapid nitrogen replenishment valve is as follows: the rapid nitrogen replenishment valve closes 0.3 to 0.5 seconds after the second gate valve completes its closing action, ensuring that the system pressure does not drop suddenly during the discharge process.

[0023] Preferably, a first oxygen content analyzer and a first water content analyzer are installed on the pipeline between the first control valve and the fifth air port of the material collector; the fifth air port of the material collector is connected to a first vent valve;

[0024] When the detection value of the first oxygen content analyzer exceeds the preset oxygen content threshold and / or the detection value of the first water content analyzer exceeds the preset water content threshold, the first vent valve is opened to vent.

[0025] Preferably, the second air port of the balance tank is connected to the eighth air port of the air compressor, and the ninth air port of the air compressor is connected to the sixth air port of the air storage tank via a second control valve; the ninth air port of the air compressor is also connected to a second vent valve.

[0026] The pipeline of the second vent valve is equipped with a second oxygen content meter and a second water content meter; when the detection value of the second oxygen content meter exceeds the preset oxygen content threshold and / or the detection value of the second water content meter exceeds the preset water content threshold, the second vent valve is opened to vent.

[0027] Preferably, the feeding device includes a feeder, and the outer cavity of the bag filter in the material collector is connected to the spiral feeding outlet of the feeder via a first material pump. The material accumulated in the outer cavity of the bag filter is transferred to the spiral feeding outlet via the first material pump, and then transferred to the material collection cylinder above the feed nozzle of the air jet mill.

[0028] The beneficial effects of the present invention are as follows: The closed-loop circulating airflow pulverizing system for material pulverization of the present invention has a three-stage air replenishment and pressure stabilization system, with no sudden pressure drop and no backflow. Through the three-stage air replenishment of the constant speed nitrogen replenishment valve, low pressure nitrogen replenishment valve, and fast nitrogen replenishment valve, combined with the balance tank to quickly stabilize the pressure, the system maintains positive pressure throughout the process and prevents the backflow of external air and moisture.

[0029] The closed-loop airflow pulverizing system for material crushing of the present invention does not compromise the airtightness during the discharge operation. It adopts a double gate valve for step-by-step material feeding, and is equipped with a rapid nitrogen replenishment valve that opens in advance and closes with a lag. The discharge pressure is stable throughout the process, without damaging the closed environment of the system, thus solving the problem of large discharge pressure fluctuations in traditional equipment.

[0030] The closed-loop airflow pulverizing system for material pulverization of the present invention adopts a closed-loop structure, combined with nitrogen protection and multi-level oxygen and water content monitoring and venting, which effectively avoids the deterioration and degradation of easily oxidized and moisture-absorbing materials such as lithium battery materials and pharmaceutical raw materials during pulverization.

[0031] The gas is deeply dried and purified by an air compressor, air tank, refrigerated dryer, and desiccant dryer before being recycled. The dew point can reach below -55℃, which greatly reduces nitrogen consumption, making operation more economical, with less nitrogen consumption and lower operating costs. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the closed-loop circulating airflow pulverizing system for material pulverization according to the present invention.

[0033] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0034] Figure 3 yes Figure 1 Enlarged view of point B in the middle;

[0035] The components include: 1. Feeding device; 11. Isolator; 12. Feeder; 13. Material transition bin; 2. Air jet mill; 21. Milling chamber; 22. Feed nozzle; 3. Second air supply system; 31. Air compressor; 32. Air storage tank; 33. Refrigerated dryer; 34. Desiccant dryer; 35. Gas buffer tank; 37. First oxygen content analyzer; 38. First water content analyzer; 4. Material collector; 41. Balance tank; 42. Bag filter; 431 432. First gate valve; 44. Second gate valve; 45. Normal speed nitrogen replenishment valve; 46. Low pressure nitrogen replenishment valve; 47. Rapid nitrogen replenishment valve; 48. Second oxygen content analyzer; 69. Second water content analyzer; 60. First control valve; 61. Second control valve; 62. Third control valve; 63. Fourth control valve; 64. Fifth control valve; 65. First vent valve; 66. Second vent valve; 67. Shut-off valve; 68. Check valve; 7. First material pump;

[0036] 411, First air inlet; 412, Second air inlet; 421, Fifth air inlet; 321, Sixth air inlet; 322, Seventh air inlet; 311, Eighth air inlet; 312, Ninth air inlet. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0038] like Figure 1 , Figure 2 , Figure 3As shown, a closed-loop circulating airflow pulverizing system for material pulverization includes a material path pipeline and an air path pipeline; the air path pipeline includes a pulverizing air path and a regulating air path.

[0039] The material pipeline is as follows: the material is fed into the air jet mill 2 through the feeding device 1 for crushing, and then discharged from the material collector 4 after gas-solid separation.

[0040] The pulverizing air path is as follows: the first air supply system is divided into two paths by a gas distributor. One path supplies the feed nozzle 22 of the airflow pulverizer 2, and the other path supplies the pulverizing chamber 21 of the airflow pulverizer 2. The pulverizing chamber 21 of the airflow pulverizer 2 is connected to the outer cavity of the bag filter 42 installed in the material collector 4.

[0041] The regulating gas path includes a balance tank 41, a constant speed nitrogen replenishment valve 44, a low pressure nitrogen replenishment valve 45, and a rapid nitrogen replenishment valve 46. The second gas supply system 3 is connected to the first gas port 411 of the balance tank 41 through the constant speed nitrogen replenishment valve 44 and the fifth control valve 65. The second gas supply system 3 is connected to the first gas port 411 of the balance tank 41 through the low pressure nitrogen replenishment valve 45 and the rapid nitrogen replenishment valve 46. The fifth gas port 421 of the material collector 4, which is connected to the inner cavity of the bag filter 42, is connected to the first gas port 411 of the balance tank 41 through the first control valve 61.

[0042] The second air port 412 of the balance tank 41 is connected to the sixth air port 321 of the air storage tank 32 in the first air supply system via the air compressor 31 and the second control valve 62.

[0043] 1. Implementation of material pipeline

[0044] The raw materials are fed into the feeding device 1 and sent to the air jet mill 2 for crushing. After crushing, the material enters the material collector 4 with the airflow and undergoes gas-solid separation through the bag filter 42. The crushed material is discharged from the bottom of the material collector 4, completing the material circulation.

[0045] Specifically, in one optional embodiment, the feeding device 1 includes an isolator 11, a material transition chamber 13, and a feeder 12. The material is fed into the isolator 11 manually or by a robot, enters the material transition chamber 13 through the pipe between the outlet of the isolator 11 and the inlet of the material transition chamber 13, and then enters the feeder 12 through the pipe between the outlet of the material transition chamber 13 and the inlet of the feeder 12.

[0046] The isolator 11 is preferably equipped with an ultraviolet sterilization device and a gas circulation purification unit to sterilize and replace the gas inside the isolator 11. The feeder 12 adopts a twin-screw structure with a feeding capacity ranging from 5-2000 kg / h. The material transition chamber 13 is preferably equipped with an inert gas replacement interface and a pneumatic discharge valve installed at the bottom. After the material enters the material transition chamber 13, the pneumatic discharge valve is closed, and the inert gas replacement interface is opened for secondary gas replacement. After the replacement is completed, the pneumatic discharge valve is opened, and the material enters the feeder 12, ensuring that any trace gas carried by the material is removed.

[0047] 2. Implementation of pulverizing gas path

[0048] The high-purity nitrogen output from the first gas supply system is divided into two paths by the gas distributor: one path supplies the feed nozzle 22 to carry the material into the crushing chamber 21; the other path directly supplies the crushing chamber 21 to provide crushing power; the outlet of the crushing chamber 21 is connected to the outer cavity of the bag filter 42 of the material collector 4 to realize gas-solid mixing and conveying.

[0049] The airflow pulverizer 2 mainly consists of a pulverizing chamber 21, a feed nozzle 22, a pulverizing disc, and a pulverizing ring. Material and pulverizing gas are injected into the pulverizing chamber 21 through the feed nozzle 22. The pulverizing ring is fixedly installed on the inner wall of the pulverizing chamber 21, forming an annular pulverizing channel with the pulverizing disc to achieve material pulverization.

[0050] 3. Implementation of air path adjustment

[0051] The second gas supply system 3 (nitrogen source) is connected to the first gas port 411 of the balance tank 41 via the rapid nitrogen replenishment valve 44 and the fifth control valve 65. The second gas supply system 3 (nitrogen source) is connected to the first gas port 411 of the balance tank 41 via the low-pressure nitrogen replenishment valve 45 and the rapid nitrogen replenishment valve 46. The fifth gas port 421 of the material collector 4, which is connected to the inner cavity of the bag filter 42, is connected to the first gas port 411 of the balance tank 41 via the first control valve 61.

[0052] The first gas supply system includes a gas storage tank 32, an air compressor 31, a refrigerated dryer 33, a desiccant dryer 34, a gas buffer tank 35, a gas distributor, and corresponding control valves.

[0053] The compressed air output from air compressor 31 first enters air storage tank 32 for pressure stabilization, and then passes through refrigerated dryer 33 and desiccant dryer 34 for deep drying. Desiccant dryer 34 adopts a dual-tower alternating working mode, with built-in 4A molecular sieve and activated alumina composite adsorbent, which can reduce the gas dew point to below -55℃. Gas distributor divides the purified gas into two paths: one path supplies the feed nozzle 22 of airflow pulverizer 2 through third control valve 63, with a working pressure of 0.1-1.3MPa; the other path supplies the pulverizing chamber 21 through fourth control valve 64 as protective gas.

[0054] The gas flow path of the pulverizing gas circuit is as follows: Second gas supply system 3 → First gas port 411 of balance tank 41 → Second gas port 412 of balance tank 41 → Air compressor 31 → Second control valve 62 → Sixth gas port 321 of gas storage tank 32 → Seventh gas port 322 of gas storage tank 32 → Refrigerated dryer 33 → Desiccant dryer 34 → Gas buffer tank 35 → Gas distributor, completing gas drying and purification; One gas supplied by the gas distributor enters the feed nozzle 22 through the third control valve 63; The other gas supplied by the gas distributor enters the pulverizing chamber 21 through the fourth control valve 64.

[0055] Specifically, in one optional embodiment, a shut-off valve 68 and a check valve 69 are connected in series between the second air port 412 of the balance tank 41 and the second control valve 62 to prevent gas backflow and protect the air compressor 31 and the air tank 32.

[0056] The second air port 412 of the balance tank 41 is arranged above the first air port 411, forming an upper and lower layered air path structure to avoid mutual interference between the replenishing air flow and the circulating air flow, and to ensure stable system operation.

[0057] Specifically, in one optional embodiment, a first pressure gauge is installed between the first air port 411 of the balance tank 41 and the fifth air port 421 of the material collector 4.

[0058] Opening conditions: The pressure measured by the first pressure test gauge is less than the 1000Pa working positive pressure threshold → the low-pressure nitrogen replenishment valve 45 is opened to replenish gas to the balance tank 41;

[0059] Closure condition: Pressure rises back to 1000Pa → Low-pressure nitrogen replenishment valve 45 closes;

[0060] Application scenario: During the standby and start-up / stop phases of the crushing process, this prevents negative pressure from drawing in air.

[0061] Specifically, in one optional embodiment, a second pressure gauge is installed on the pipeline from the gas distributor to the pulverizing chamber 21;

[0062] Opening conditions: Pressure < 0.8MPa working positive pressure lower limit threshold → constant speed nitrogen replenishment valve 44 opens, replenishing gas to balance tank 41 at a constant flow rate (flow rate for example: 10Nm³ / h);

[0063] Closure condition: Pressure rises back to the upper limit threshold of 1.1MPa working positive pressure → constant speed nitrogen replenishment valve 44 closes;

[0064] Function: To ensure that the system pressure remains stable and without fluctuations during material crushing.

[0065] Specifically, in one optional embodiment, a double discharge valve is installed below the material collector 4: the upper one is a first gate valve 431, and the lower one is a second gate valve 432;

[0066] Discharge sequence:

[0067] ① 0.3 to 0.5 seconds before the first gate valve 431 opens, the rapid nitrogen replenishment valve 46 immediately opens, instantly replenishing the balance tank 41 with a flow rate of 30 to 60 Nm³ / h, thus raising the system pressure in advance;

[0068] ② The first gate valve 431 opens → the material falls into the temporary storage chamber between the two valves. At this time, the quick nitrogen replenishment valve 46 remains open to maintain the positive pressure of the system.

[0069] ③ First gate valve 431 closes → second gate valve 432 opens → material is discharged, and rapid nitrogen replenishment valve 46 continuously replenishes air to offset the pressure drop caused by material discharge;

[0070] ④ After the second gate valve 432 closes, 0.3 to 0.5 seconds later, the rapid nitrogen replenishment valve 46 closes, ending this instantaneous nitrogen replenishment.

[0071] Application effect: The pressure does not drop suddenly throughout the discharge process, and the water-free and oxygen-free environment is not destroyed.

[0072] Specifically, in one optional embodiment, a first oxygen content analyzer 37 and a first water content analyzer 38 are installed between the first control valve 61 and the fifth gas port 421.

[0073] The fifth air port 421 is connected to the first vent valve 66;

[0074] Triggering logic: Oxygen content > 30ppm or water content > 30ppm → First vent valve 66 opens to vent unqualified gas;

[0075] Control targets: During crushing, oxygen content ≤25ppm, water content ≤25ppm.

[0076] Specifically, in one optional embodiment, the ninth air port 312 of the air compressor 31 is equipped with a second oxygen content analyzer 47, a second water content analyzer 48 and a second vent valve 67.

[0077] Trigger logic: Oxygen content > 30ppm or water content > 30ppm → Second vent valve 67 opens;

[0078] Function: To perform secondary monitoring and purification of circulating gas to ensure that the gas entering the gas storage tank 32 meets the requirements of being anhydrous and oxygen-free.

[0079] Specifically, in one optional embodiment, the outer cavity of the bag filter 42 of the material collector 4 is returned to the feeder 12 via the first material pump 7 to achieve coarse powder recycling and crushing.

[0080] Coarse powder return path: outer cavity of bag filter 42 → first material pump 7 → screw feeder 12 → material collection cylinder of air jet mill 2;

[0081] Coarse powder in the material that does not meet the required fineness is intercepted by the bag filter 42 and sent back to the feeder 12 by the first material pump 7, and re-enters the crushing chamber 21 for cyclic crushing.

[0082] Specifically, in one optional embodiment, the material discharged through the second gate valve 432 can also be returned to the inlet of the isolator 11 through the recovery pipeline, and then sterilized or gas-purified again before being crushed again.

[0083] Example 1: Crushing of Lithium-ion Battery Cathode Material LPSC

[0084] System Configuration:

[0085] Feeding device 1: Isolator 11 with a volume of 500L, material transfer bin 13 with a volume of 100L;

[0086] Airflow pulverizer 2: Pulverizing chamber 21 with a diameter of 500 mm and a pulverizing pressure of 1.1 MPa;

[0087] Gas buffer tank 35, volume 5000L; balance tank 41, volume 5000L; material collector 4, filtration area 40m².

[0088] Operating steps:

[0089] Air compressor 31 starts to purge the entire system with nitrogen. Purge is stopped when the oxygen content measured by the first oxygen content meter 37 and the second oxygen content meter 47 is less than 25 ppm, and the water content measured by the first water content meter 38 and the second water content meter 48 is less than 25 ppm.

[0090] Add LPSC raw material to isolator 11, close the feed gate, and allow internal gas replacement for 50 minutes. Then turn on feeder 12 and set the feeding speed to 150 kg / h. Start air jet mill 2 and set the grinding pressure to 1.1 MPa.

[0091] After being crushed, the material enters the material collector 4, and the pressure in the balance tank 41 is maintained at 1-2 kPa. The double discharge valve is then activated to discharge the material.

[0092] Testing revealed that the moisture content of the pulverized LPSC powder was 4.8 ppm, with no agglomeration and an average particle size D50 of 0.5 μm, meeting the quality requirements for high-purity lithium battery materials.

[0093] Example 2: Crushing of LGPS, a lithium-ion battery cathode material

[0094] System Configuration:

[0095] Feeding device 1: Isolator 11 with a volume of 500L, material transfer bin 13 with a volume of 100L;

[0096] Airflow pulverizer 2: Pulverizing chamber 21 with a diameter of 500 mm and a pulverizing pressure of 0.9 MPa;

[0097] Gas buffer tank 35, volume 5000L; balance tank 41, volume 5000L; material collector 4, filtration area 40m².

[0098] Operating steps:

[0099] Air compressor 31 starts to purge the entire system with nitrogen. Purge is stopped when the oxygen content measured by the first oxygen content meter 37 and the second oxygen content meter 47 is less than 25 ppm, and the water content measured by the first water content meter 38 and the second water content meter 48 is less than 25 ppm.

[0100] Add the LGPS raw material to the isolator 11, close the feed door, and allow internal gas replacement for 50 minutes. Then, turn on the feeder 12 and set the feeding speed to 150 kg / h. Start the air jet mill 2 and set the milling pressure to 0.9 MPa.

[0101] After being crushed, the material enters the material collector 4, and the pressure in the balance tank 41 is maintained at 1-2 kPa. The double discharge valve is then activated to discharge the material.

[0102] Experimental results: The moisture content of the pulverized LGPS powder was 5.6 ppm, with no agglomeration and an average particle size D50 of 3 μm, which meets the quality requirements of high-purity lithium battery materials.

[0103] Example 3: Crushing of Li2S, a lithium-ion battery cathode material

[0104] System Configuration:

[0105] Feeding device 1: Isolator 11 with a volume of 500L, material transfer bin 13 with a volume of 100L;

[0106] Airflow pulverizer 2: Pulverizing chamber 21 with a diameter of 500 mm and a pulverizing pressure of 0.6 MPa;

[0107] Gas buffer tank 35, volume 5000L; balance tank 41, volume 5000L; material collector 4, filtration area 40m².

[0108] Operating steps:

[0109] Air compressor 31 starts to purge the entire system with nitrogen. Purge is stopped when the oxygen content measured by the first oxygen content meter 37 and the second oxygen content meter 47 is less than 25 ppm, and the water content measured by the first water content meter 38 and the second water content meter 48 is less than 25 ppm.

[0110] Add Li2S raw material to isolator 11, close the feed gate, and allow internal gas replacement for 50 minutes. Then turn on feeder 12 and set the feeding speed to 150 kg / h. Start air jet mill 2 and set the grinding pressure to 0.6 MPa.

[0111] After being crushed, the material enters the material collector 4, and the pressure in the balance tank 41 is maintained at 1-2 kPa. The double discharge valve is then activated to discharge the material.

[0112] Testing revealed that the moisture content of the pulverized Li2S powder was 5.8 ppm, with no agglomeration and an average particle size D50 of 15 μm, meeting the quality requirements for high-purity lithium battery materials.

[0113] The above description is merely a specific embodiment of the present invention. Various examples and illustrations do not constitute a limitation on the substantive content of the present invention. Those skilled in the art can modify or transform the specific embodiments described above after reading the specification without departing from the essence and scope of the invention.

Claims

1. A closed-loop circulating airflow pulverizing system for material crushing, characterized in that, This includes material supply pipelines and air supply pipelines; the air supply pipelines include a crushing air supply and a regulating air supply. The material pipeline is as follows: the material is fed into the airflow pulverizer (2) through the feeding device (1) for pulverization, and then discharged through the material collector (4) after gas-solid separation; The pulverizing air path is as follows: the first air supply system is divided into two paths by a gas distributor. One path supplies the feed nozzle (22) of the airflow pulverizer (2), and the other path supplies the pulverizing chamber (21) of the airflow pulverizer (2). The pulverizing chamber (21) of the airflow pulverizer (2) is connected to the outer cavity of the bag filter (42) set in the material collector (4). The regulating gas path includes a balance tank (41), a constant speed nitrogen replenishment valve (44), a low pressure nitrogen replenishment valve (45), and a fast nitrogen replenishment valve (46). The second gas supply system (3) is connected to the first gas port (411) of the balance tank (41) through the constant speed nitrogen replenishment valve (44) and the fifth control valve (65). The second gas supply system (3) is connected to the first gas port (411) of the balance tank (41) through the low pressure nitrogen replenishment valve (45) and the fast nitrogen replenishment valve (46). The fifth gas port (421) of the material collector (4) connected to the inner cavity of the bag filter (42) is connected to the first gas port (411) of the balance tank (41) through the first control valve (61). The second air port (412) of the balance tank (41) is connected to the sixth air port (321) of the air storage tank (32) in the first air supply system via the air compressor (31) and the second control valve (62). The rapid nitrogen replenishment valve (46) is used for instantaneous pressure compensation during material discharge. The material collector (4) is equipped with a double discharge valve below it; the double discharge valve includes a first gate valve (431) and a second gate valve (432) connected in series; the discharge process is as follows: the first gate valve (431) is opened, and the material falls into the temporary storage cavity between the first gate valve (431) and the second gate valve (432); after the first gate valve (431) is closed, the second gate valve (432) is opened to allow the material to be discharged from the temporary storage cavity; The opening conditions for the rapid nitrogen replenishment valve (46) are as follows: The rapid nitrogen replenishment valve (46) opens 0.3 to 0.5 seconds before the first gate valve (431) performs its opening action, and replenishes the balance tank (41) with gas; The closing condition of the rapid nitrogen replenishment valve (46) is that the rapid nitrogen replenishment valve (46) closes 0.3 to 0.5 seconds after the second gate valve (432) completes its closing action.

2. The closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, The seventh gas port (322) of the gas storage tank (32) is connected to the gas distributor via the refrigerated dryer (33), the desiccant (34), and the gas buffer tank (35). The gas distributor is connected to the feed nozzle (22) of the air jet mill (2) via the third control valve (63). The gas distributor is connected to the grinding chamber (21) of the air jet mill (2) via the fourth control valve (64).

3. The closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, A shut-off valve (68) and a check valve (69) are connected between the second air port (412) of the balance tank (41) and the second control valve (62); the second air port (412) of the balance tank (41) is located above the first air port (411) of the balance tank (41).

4. A closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, A first pressure gauge is installed on the pipeline between the first air port (411) of the balance tank (41) and the fifth air port (421) of the material collector (4); The opening condition of the low-pressure nitrogen replenishment valve (45) is as follows: when the real-time pressure measured by the first pressure test gauge is less than the set working positive pressure threshold, the second gas supply system (3) replenishes nitrogen into the balance tank (41) through the opened low-pressure nitrogen replenishment valve (45) to increase the gas pressure in the regulating gas path. The closing condition of the low-pressure nitrogen replenishment valve (45) is: when the real-time pressure measured by the first pressure test gauge after replenishment is greater than or equal to the working positive pressure threshold, it is closed.

5. A closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, A second pressure gauge is installed on the pipeline from the gas distributor to the pulverizing chamber (21) of the airflow pulverizer (2); When the real-time pressure measured by the second pressure gauge is lower than the set lower limit threshold of the working positive pressure, the constant speed nitrogen replenishment valve (44) opens, and the second gas supply system (3) replenishes nitrogen into the balance tank (41) through the opened constant speed nitrogen replenishment valve (44) and the fifth control valve (65). When the real-time pressure measured by the second pressure test gauge after gas replenishment rises back to the set upper limit threshold of the working positive pressure, the constant speed nitrogen replenishment valve (44) closes.

6. A closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, A first oxygen content analyzer (37) and a first water content analyzer (38) are installed on the pipeline between the first control valve (61) and the fifth air port (421) of the material collector (4); the fifth air port (421) of the material collector (4) is connected to the first vent valve (66). When the detection value of the first oxygen content analyzer (37) exceeds the preset oxygen content threshold and / or the detection value of the first water content analyzer (38) exceeds the preset water content threshold, the first vent valve (66) is opened to vent.

7. A closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, The second air port (412) of the balance tank (41) is connected to the eighth air port (311) of the air compressor (31), and the ninth air port (312) of the air compressor (31) is connected to the sixth air port (321) of the air storage tank (32) via the second control valve (62); the ninth air port (312) of the air compressor (31) is also connected to the second vent valve (67). The pipeline of the second vent valve (67) is equipped with a second oxygen content meter (47) and a second water content meter (48); when the detection value of the second oxygen content meter (47) exceeds the preset oxygen content threshold and / or the detection value of the second water content meter (48) exceeds the preset water content threshold, the second vent valve (67) is opened to vent.

8. A closed-loop circulating airflow pulverizing system for material pulverization according to claim 1, characterized in that, The feeding device (1) includes a feeder (12). The outer cavity of the bag filter (42) installed in the material collector (4) is connected to the spiral feeding outlet of the feeder (12) via the first material pump (7). The material accumulated in the outer cavity of the bag filter (42) is transferred to the spiral feeding outlet via the first material pump (7) and then transferred to the material collection cylinder installed above the feed nozzle (22) of the airflow pulverizer (2).

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