Process for reducing dust in production process of bright silver powder

Abstract

The invention provides a process for reducing dust in a bright silver powder production process, and relates to the technical field of powder processing, the process comprises the following steps: S1, selecting stainless steel balls with the diameter of 3-10mm as a grinding medium, controlling the ball-to-material ratio to be 10: (1-3), performing ball milling for 12-24 hours by using a planetary ball mill at the rotating speed of 200-300r / min, and controlling the temperature to be 30-40 DEG C; s2, a solvent is added into the ball milling tank, the ratio of the silver powder to the solvent is 1: (2-3), ball milling continues to be conducted for 2 min, the rotating speed is reduced to 100-150 r / min, and the solvent is sprayed into the ball mill through a solvent adding spray gun; s3, the materials are screened through a vibrating screen, the mesh number of the screen is 10-40 meshes, and dust is collected through a dust suction device in the screening process, S4, an undersize silver powder mixture is poured into a filter vat, and natural filtering is conducted for 5-12 hours through a 800-1000-mesh filter screen; s5, drying at 30-40 DEG C for 12-18 hours, wherein the thickness of a silver filter cake is not more than 2cm; and S6, sieving by using a 100-300-mesh ultrasonic vibrating screen. According to the grinding device, dust generated in the bright silver powder grinding process can be effectively reduced, dust overflow is avoided, and the production operation environment is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of powder processing, and in particular to a process for reducing dust in the production process of bright silver powder. Background Art

[0002] Bright silver powder is the main conductive filler of polymer silver paste, which is used in the production and preparation of electronic materials and devices such as conductive adhesives, touch screens, and membrane switches, and has a wide range of applications in the fields of electronics, communication, photovoltaic, etc.; with the rapid development of the domestic electronics, communication, and clean energy industries, its usage is increasing.

[0003] Bright silver powder is generally produced by a dry mechanical ball milling process. The main process route is ball milling, ball-powder separation, cleaning, drying, sieving, inspection and packaging. The ball-powder separation process is mostly manually processed, and the dust is relatively large; researching a process that meets the product quality and technical requirements and has less dust in the process is one of the important technical means to improve the direct silver recovery rate and improve the working environment. Summary of the Invention

[0004] In view of the above problems, the present invention provides a process for reducing dust in the production process of bright silver powder. The invention can effectively reduce the dust in the grinding process of bright silver powder, avoid dust spillage, and greatly improve the production working environment.

[0005] To solve the above problems, the technical solution adopted by the present invention is: A process for reducing dust in the production process of bright silver powder, comprising the following steps: S1. Select stainless steel balls with a diameter of 3-10 mm as the grinding medium, the ball-to-material ratio is 10:1-3, use a planetary ball mill to ball mill at a speed of 200-300 r / min for 12-24 hours, and control the temperature at 30-40 °C; S2. Add a solvent to the ball mill tank, the ratio of silver powder to solvent is 1:2-3, continue to ball mill for 2 minutes, reduce the speed to 100-150 r / min, and use a solvent addition spray gun to spray the solvent into the ball mill; S3. Screen the material through a vibrating screen, the mesh number of the screen is 10-40 meshes, and use a dust collection device to collect dust during the screening process; S4. Pour the screened silver powder mixture into a filtering bucket, and naturally filter it with an 800-1000 mesh filter screen for 5-12 hours; S5. Dry at 30-40 °C for 12-18 hours, and the thickness of the silver filter cake does not exceed 2 cm; S6. Screen with a 100-300 mesh ultrasonic vibrating screen, and hermetically collect the screened silver powder.

[0006] Through dry ball milling, the ball-to-material ratio and process parameters are optimized to improve the silver powder grinding efficiency and reduce energy consumption and wear. During the wet ball milling stage, a solvent spray gun is used to accurately add solvents, which significantly reduces dust flying and improves the production environment. The process is controlled in stages (ball milling, screening, filtering, drying, etc.) to ensure that the silver powder has uniform particle size and high purity to meet industrial needs. Ultrasonic vibration screening reduces the risk of blockage, improves screening efficiency, and ensures the stable quality of the finished silver powder.

[0007] Preferably, the stainless steel balls are mixed in different diameter ratios, the raw silver powder has a purity of more than 99.9%, and a particle size distribution of 1-5 μm.

[0008] Mixed diameter stainless steel balls improve grinding efficiency and make silver powder particles more uniform; high purity (more than 99.9%) and specific particle size (1-5μm) raw silver powder ensure excellent performance of the final product.

[0009] Preferably, the solvent adding spray gun comprises a positioning cylinder, a spray head and a spray device, and the spray head is connected to a driving motor through a telescopic end, and can deflect and spray the solvent so that the solvent is sprayed in a fan-shaped area.

[0010] The above method can expand the area where the solvent is sprayed, so that the solvent and silver powder can be mixed more effectively and fully, and at the same time, the humidity inside the ball mill can be increased and the generation of dust can be reduced.

[0011] Preferably, the spray device comprises a spray base and a spray hole, and the spray base is located in the feeding channel and continuously generates water mist to prevent dust from spilling out.

[0012] By providing the above structure, dust spillage can be effectively avoided, greatly improving the working environment.

[0013] Preferably, a driving piston and a storage chamber are provided in the positioning cylinder, and the solvent is pumped into the storage chamber through a delivery pipeline and sprayed out from the spray head and the spray device.

[0014] Through the above structural design, there is no need to install a long delivery hose on the outside of the nozzle 500. The liquid solvent can be transported by utilizing the positioning cylinder 100 and the internal structure of the telescopic end 600, thereby ensuring the stability of normal pumping of the solvent, which is particularly suitable for the complex environment around the ball mill.

[0015] Preferably, the mesh of the vibrating screen is made of stainless steel, and the installation level error does not exceed ±0.5 mm.

[0016] Preferably, the filter barrel is made of corrosion-resistant plastic material, and the filter screen is made of polyester fiber material.

[0017] Preferably, a forced air oven is used, the temperature fluctuation does not exceed ±1°C, and is monitored in real time by a temperature sensor.

[0018] Preferably, the ultrasonic power and frequency of the ultrasonic vibrating screen are matched with the vibration parameters, and the coarse particles on the screen are returned to the ball milling process.

[0019] Preferably, a circulating water cooling system is used to control the temperature in both the dry ball milling stage and the wet ball milling stage.

[0020] The beneficial effects of the present invention are as follows: Compared with the prior art, through the process idea of dry + wet combined ball milling, ball powder separation, filtration, drying, sieving, and inspection and packaging, it can effectively reduce the dust in the grinding process of bright silver powder, avoid dust overflow, and greatly improve the production operation environment. Description of the Drawings

[0021] Figure 1 It is a schematic three-dimensional structure diagram of the solvent addition spray gun of the present invention.

[0022] Figure 2 For the present invention Figure 1 The schematic front view structure diagram.

[0023] Figure 3 For the present invention Figure 2 The enlarged structure diagram at A of the present invention.

[0024] Figure 4 For the present invention Figure 2 The enlarged structure diagram at B of the present invention.

[0025] In the figure: 100, positioning cylinder; 1001, storage chamber; 110, first driving rod; 120, second driving rod; 200, spraying device; 210, spraying base; 220, spraying holes; 300, conveying pipeline; 400, connecting hose; 500, nozzle; 600, telescopic end; 700, driving motor; 710, driving rotating shaft. Detailed Embodiments

[0026] The present invention will be further described below with reference to the drawings and embodiments.

[0027] A process for reducing dust in the production process of bright silver powder includes the following steps: Stage 1: Dry ball milling stage Ball material selection and ratio Stainless steel balls with high hardness and good wear resistance are selected as the grinding medium, and their diameter ranges from 3 to 10 mm. Stainless steel balls of different diameters are mixed in a certain proportion to improve the ball milling efficiency; the ball-to-material ratio is strictly controlled within 10:1 - 3. This ratio has been verified through a large number of experiments. Within this range, it can ensure that the silver powder is fully ground during the ball milling process, and at the same time, it can avoid excessive energy waste and increased wear of the ball milling tank caused by too large a ball-to-material ratio.

[0028] The raw material silver powder should be high-purity silver powder with a purity above 99.9%, and its particle size distribution should be between 1 - 5μm to ensure the quality of the final product.

[0029] Ball milling equipment and parameters Use a planetary ball mill with precise temperature and rotation speed control functions. This equipment can provide a stable and efficient ball milling environment; the ball milling time is set to 12 - 24 hours, and the rotation speed of the ball mill is controlled at 200 - 300 r / min. During the ball milling process, the temperature inside the ball milling tank is monitored in real time, and the temperature is controlled at 30 - 40°C through a circulating water cooling system to prevent the oxidation or agglomeration of silver powder due to excessive temperature.

[0030] Stage 2: Wet ball milling stage Solvent selection and addition The solvent can preferably be anhydrous ethanol because of its good solubility and volatility and its non-corrosiveness to silver powder; the ratio of silver powder to solvent is strictly controlled at 1:2 - 3. After accurately measuring the required solvent, it is slowly added to the ball milling tank to avoid solvent splashing and silver powder agglomeration.

[0031] Ball milling operation and control After adding the solvent, continue ball milling for 2 min. At this time, the rotation speed of the ball mill is appropriately reduced to 100 - 150 r / min to fully mix the solvent and silver powder, while reducing the impact force during ball milling to prevent excessive fragmentation of silver powder; during the ball milling process, turn on the stirring device of the ball milling tank to ensure uniform mixing of the materials.

[0032] In the wet ball milling stage, a solvent addition spray gun is used, which includes a positioning cylinder 100. The positioning cylinder 100 has a hollow design inside. A spray head 500 is provided at the first end of the positioning cylinder 100. Through the spray head 500, the solvent can be sprayed into the ball mill and mixed with the materials inside the ball mill to avoid generating excessive dust.

[0033] The spray gun here can extend from the horizontal axis of the ball mill into the ball mill and spray the solvent; the spray gun here also includes a telescopic end 600. The telescopic end 600 is rotatably connected to the spray head 500, and the spray head 500 can rotate relative to the telescopic end 600. A driving motor 700 is installed outside the telescopic end 600 to drive and control the deflection of the spray head 500. By controlling the deflection of the spray head 500, the solvent sprayed by the spray head 500 can be sprayed in a fan-shaped area and can be sprayed to various positions inside the ball mill, improving the mixing effect of the solvent and the powder, improving the overall mixing efficiency, and greatly shortening the overall processing time.

[0034] A spray device 200 is also installed outside the positioning cylinder 100. Through the spray device 200, atomized water mist can be continuously generated, which can create a barrier around the positioning cylinder 100 to prevent powder from overflowing from this place. Here, the spray device 200 includes a spray base 210 and spray holes 220. Here, the spray base 210 is installed on one side close to the nozzle 500; during use, the spray base 210 is located in the feeding channel and does not enter the interior of the ball mill, and can continuously generate water mist within a relatively small size range, avoiding the overflow of dust.

[0035] A driving piston is also hermetically and slidably connected inside the positioning cylinder 100. A first driving rod 110 is fixed on the first side of the driving piston, and a second driving rod 120 is fixed on the second side. Here, the second driving rod 120 is externally connected to a power source to control the horizontal movement of the driving piston. Here, the end of the first driving rod 110 penetrates through the positioning cylinder 100 and is hermetically and slidably connected thereto. The end of the first driving rod 110 is connected to the telescopic end 600 and can drive the telescopic end 600 to drive the nozzle 500 to linearly move.

[0036] A storage chamber 1001 is formed between the driving piston and the inner wall of the positioning cylinder 100. Through the storage chamber 1001, a liquid solvent can be stored. A delivery pipe 300 is installed outside the storage chamber 1001. Through the delivery pipe 300, the solvent can be pumped into the storage chamber 1001. Finally, the solvent can be sprayed out from the nozzle 500 and the spray device 200. The solvent sprayed out from the nozzle 500 can directly enter the interior of the ball mill, and the solvent sprayed out from the spray device 200 can form a spray to create an isolation barrier to prevent dust from overflowing.

[0037] Here, both the spray device 200 and the nozzle 500 are communicated with the storage chamber 1001. While pumping the solvent into the storage chamber 1001, the nozzle 500 at the end can spray out the solvent, and the spray device 200 can atomize to generate water mist to form a barrier.

[0038] Here, the telescopic end 600 can be selected as a hollow pipe. The nozzle 500 is communicated with the telescopic end 600 through a connecting hose 400. Here, the telescopic end 600 is communicated with the storage chamber 1001. Through the above structural design, there is no need to install a long delivery hose outside the nozzle 500, and the internal structure of the positioning cylinder 100 and the telescopic end 600 can be used to deliver the liquid solvent, ensuring the stability of the normal pumping of the solvent, especially suitable for the complex environment around the ball mill.

[0039] Stage Three: Ball-Powder Separation Stage Vibrating Screen Selection and Installation Select a vibrating screen with good vibration performance and screening efficiency, and the mesh number of the screen is selected from 10 to 40 meshes; the screen material is made of stainless steel, which has high strength and corrosion resistance; when installing the vibrating screen, ensure that its level error does not exceed ±0.5 mm to ensure the uniformity of the screening effect.

[0040] Material transfer and screening After opening the ball mill tank, use sealed pipelines and conveying equipment to transfer the material to the vibrating screen to reduce dust flying during the transfer process; during the screening process, adjust the amplitude and frequency of the vibrating screen to evenly distribute the material on the screen surface and improve the screening efficiency; at the same time, install a dust collection device above the vibrating screen to collect a small amount of dust generated during the screening process and further improve the working environment.

[0041] Stage Four: Filtration stage Selection of filter barrel and filter screen The filter barrel is made of corrosion-resistant plastic material, and its internal structure is reasonably designed to facilitate the entry and exit of materials and cleaning; the filter screen is selected as a polyester fiber filter screen with 800 - 1000 meshes, which has good filtering performance and mechanical strength. When installing the filter screen, ensure that the filter screen is well sealed with the filter barrel to prevent material leakage.

[0042] Filtration operation and control Slowly pour the undersize silver powder mixture into the filter barrel for natural filtration. The filtration time is controlled within 5h - 12h, and the filtration time can be appropriately adjusted according to the properties of the material and the filtration situation; during the filtration process, regularly check the liquid level in the filter barrel and the clogging situation of the filter screen, and clean or replace the filter screen in time if there is clogging.

[0043] Stage Five: Drying stage Selection of oven and parameter setting Select a forced-air oven, which has good temperature uniformity and ventilation performance. The drying temperature is set at 30 - 40 °C, and the time is 12h - 18h; during the drying process, the temperature inside the oven is monitored in real time through a temperature sensor to ensure that the temperature fluctuation range does not exceed ±1 °C; at the same time, adjust the air blowing speed to make the air circulation in the oven good and accelerate the volatilization of the solvent.

[0044] Placement of silver filter cake and monitoring of drying process Evenly spread the silver filter cake on the tray inside the oven, with a thickness not exceeding 2 cm to ensure the uniformity of the drying effect; during the drying process, regularly observe the state of the silver filter cake, such as color, shape, etc., and adjust the drying parameters in time if there is any abnormality.

[0045] Stage Six: Sieving stage Selection of ultrasonic vibrating screen and parameter setting Select a vibrating screen equipped with an ultrasonic generating device, and the mesh number of the screen is 100 mesh - 300 mesh. The ultrasonic vibrating screen can effectively prevent silver powder from clogging on the screen and improve the screening efficiency; adjust the power and frequency of the ultrasonic wave to match the vibration parameters of the vibrating screen to achieve the best screening effect.

[0046] Screening operation and finished product collection Slowly add the dried silver powder into the ultrasonic vibrating screen for screening; during the screening process, control the feeding speed to avoid material accumulation; the coarse-grained silver powder on the screen can be returned to the ball milling process for re-grinding, and the finished silver powder under the screen is collected using a sealed container to prevent secondary pollution.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A process for reducing dust in the production process of bright silver powder, characterized in that, It includes the following steps: S1. Select stainless steel balls with a diameter of 3 - 10 mm as the grinding medium, with a ball-to-material ratio of 10:1 - 3. Use a planetary ball mill to mill for 12 - 24 hours at a rotational speed of 200 - 300 r / min, and control the temperature at 30 - 40 °C; S2. Add a solvent to the ball mill tank, with a silver powder-to-solvent ratio of 1:2 - 3. Continue to mill for 2 minutes, reduce the rotational speed to 100 - 150 r / min, and use a solvent addition spray gun to spray the solvent into the ball mill; S3. Screen the material through a vibrating screen with a mesh number of 10 - 40 meshes, and use a dust collection device to collect dust during the screening process; S4. Pour the screened silver powder mixture into a filter bucket and naturally filter it through an 800 - 1000 mesh filter screen for 5 - 12 hours; S5. Dry it at 30 - 40 °C for 12 - 18 hours, with the thickness of the silver filter cake not exceeding 2 cm; S6. Screen it through a 100 - 300 mesh ultrasonic vibrating screen, and hermetically collect the screened silver powder.

2. The process according to claim 1, characterized in that, The stainless steel balls are mixed in different diameter ratios, and the purity of the raw silver powder is above 99.9%, with a particle size distribution of 1 - 5 μm.

3. The process according to claim 1, characterized in that, The solvent addition spray gun includes a positioning cylinder (100), a spray head (500), and a spraying device (200). The spray head (500) is connected to a drive motor (700) through a telescopic end (600), and can deflect and spray the solvent so that the solvent is sprayed out in a fan-shaped area.

4. The process according to claim 3, characterized in that, The spraying device (200) includes a spraying base (210) and spraying holes (220). The spraying base (210) is located in the feeding channel and continuously generates water mist to prevent dust from overflowing.

5. The process according to claim 3, characterized in that, A drive piston and a storage chamber (1001) are provided in the positioning cylinder (100). The solvent is pumped into the storage chamber (1001) through a conveying pipeline (300) and sprayed out from the spray head (500) and the spraying device (200).

6. The process according to claim 1, characterized in that, In step S3, the screen mesh of the vibrating screen is made of stainless steel, and the installation level error does not exceed ±0.5 mm.

7. The process according to claim 1, characterized in that, In step S4, the filter bucket is made of corrosion-resistant plastic, and the filter screen is made of polyester fiber.

8. The process according to claim 1, characterized in that, In step S5, a blast drying oven is used, with a temperature fluctuation not exceeding ±1 °C, and it is monitored in real time through a temperature sensor.

9. The process according to claim 1, characterized in that, In step S3, the ultrasonic power and frequency of the ultrasonic vibrating screen are matched with the vibration parameters, and the coarse particles on the screen are returned to the ball milling process.

10. The process according to claim 1, characterized in that, Both the dry ball milling stage and the wet ball milling stage use a circulating water cooling system to control the temperature.

Images