A method for grinding material by using a dry stirred mill

Abstract

The present application belongs to the field of grinding technology, and discloses a method for grinding material by using dry stirring mill. The material to be ground is sent from a bin A to a dry stirring mill I through a feeder for grinding. The ground material is cooled and transported, and then sent to a gas-solid separation device for gas-solid separation. The solid obtained after gas-solid separation is sent to a bin B. When all the material to be ground in the bin A enters the dry stirring mill I, the bin A stops feeding, the solid obtained after gas-solid separation stops entering the bin B and starts entering the bin A, the bin B starts feeding the dry stirring mill I, until all the material to be ground in the bin B enters the dry stirring mill I. Then, the bin B stops feeding, the solid obtained after gas-solid separation stops entering the bin A and starts entering the bin B, and the bin A starts feeding the dry stirring mill I. The above process is repeated for multiple times to grind the material. The present application improves the grinding efficiency and accelerates the grinding speed.

Description

Technical Field

[0001] This invention belongs to the field of grinding technology, and mainly relates to a method for grinding materials using a dry stirring mill. Background Technology

[0002] Dry stirred milling is a method for grinding submicron particles. As the name suggests, it uses dry stirred milling to grind materials. It utilizes various supporting equipment such as feeders, classifiers, dust collectors, fans, and conveying facilities; different grinding media (size, gradation, material); different grinding aid formulations (type, addition mode, and dosage); and different methods for material processing, such as batch grinding, open-circuit grinding, and closed-circuit grinding. The feed particle size and gradation are specified; and the desired effects are defined, such as product fineness, particle morphology, particle size distribution, and output. Using dry stirred milling, materials with a feed size of less than 1-3 mm can achieve a product fineness of less than 1 µm, or even nanometers.

[0003] Existing dry stirred mills generally employ batch grinding, open-circuit, or closed-circuit classifier processes, which cannot achieve the submicron and nanometer fineness of wet stirred mills. This is because in the batch grinding process of dry stirred mills, the mill grinds for extended periods, preventing heat dissipation and generating high temperatures within the grinding chamber, causing grinding aids to become ineffective and leading to machine failure. In open-circuit grinding, the residence time of the material in the mill is too short to reach the submicron level, and the material temperature is extremely high, resulting in agglomeration. In the closed-circuit classifier process, the residence time of the material in the dry stirred mill is too short, resulting in insufficient submicron components in the mill output before entering the classifier, thus failing to achieve the submicron level.

[0004] In dry stirred mill ultrafine grinding systems, the friction, shearing, and rolling forces between the grinding media, between the grinding media and the material, and between the grinding media and the inner wall of the grinding chamber are extremely intense. This causes the grinding media and material in the grinding chamber to heat up rapidly, releasing the inherent moisture of the material. Excess energy causes changes in the internal structure of the material, and the particle surface becomes charged, leading to the agglomeration of fine particles. The finer the particles, the more severe the agglomeration. Agglomerated powder and an environment with appropriate moisture will cause fine particles to coat the surface of the grinding balls, causing the grinding media to lose its grinding ability, increasing the diameter of the grinding media, and causing the grinding chamber to lose space to accommodate more material, resulting in a bloating phenomenon. The motor power increases rapidly, and the grinding disc may be jammed due to overload, causing the mill to shut down. Adding a suitable grinding aid can shield these charges and alleviate agglomeration, but when the temperature in the grinding chamber is too high, such as exceeding 100-200 degrees Celsius, the chemical properties of the grinding aid will also change, and it will lose its effect. Summary of the Invention

[0005] To achieve submicron and nanometer dry grinding of materials using a dry stirred mill, the purpose of this invention is to disclose a method for grinding materials using a dry stirred mill.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for grinding materials using a dry stirred mill includes at least two silos, namely silo A and silo B. The material to be ground is fed from silo A into the dry stirred mill I via a feeder. The ground material is cooled and conveyed, and then sent to a gas-solid separator for gas-solid separation. The solid obtained after gas-solid separation is sent to the second silo, silo B. Once all the material to be ground in silo A has entered the dry stirred mill I, silo A stops feeding material into the dry stirred mill I. The solid obtained after gas-solid separation stops entering silo B and is instead fed into silo A. Silo B then feeds material into the dry stirred mill I. This process is repeated multiple times until the material to be ground meets the grinding requirements, completing the grinding process.

[0008] A conveying and cooling pipeline is provided between the dry stirred mill I and the gas-solid separation equipment for cooling and conveying the ground material; the conveying and cooling pipeline provides cooling gas for cooling and conveying the ground material through a cooling fan.

[0009] The cooling gas is air, nitrogen, or argon.

[0010] The grinding media in the dry stirred mill I has a particle size of 3-8mm and can be made of wear-resistant materials such as alloy steel, hard alloy, and ceramics.

[0011] When the particle size requirements of the product are more stringent, the discharge end of the dry mixing mill I is equipped with a classifier to classify the material that has been milled multiple times and remove large particles.

[0012] The material after being ground multiple times by the dry stirred mill I enters the silo C. A dry stirred mill II is installed in the silo C to disperse the particle agglomerates in the material after being ground multiple times by the dry stirred mill I. The outlet of the dry stirred mill II is connected to a classifier. The classifier separates the fine particles into the product, and the coarse particles are returned to the dry stirred mill I for further grinding.

[0013] To better disperse agglomerates, the dry stirred mill II uses a grinding medium of 30-500 micrometers and an impeller edge rotation speed of 10-20 m / s.

[0014] This invention discloses a method for grinding materials using a dry stirred mill. With the dry stirred mill I running continuously, two silos circulate and feed the material to the dry stirred mill I. Specifically, the material to be ground is fed into the dry stirred mill I from silo A for grinding. The ground material is then cooled and conveyed, and the cooled material is sent to a gas-solid separation device for gas-solid separation. The solid obtained after gas-solid separation is sent to silo B. Once all the material to be ground in silo A has entered the dry stirred mill I, silo A stops feeding the dry stirred mill I. The solid obtained after gas-solid separation stops entering silo B and enters silo A instead. Silo B then feeds the dry stirred mill I until all the material to be ground in silo B has entered the dry stirred mill. Then, silo B stops feeding material to dry stirred mill I. The solid obtained after gas-solid separation stops entering silo A and is sent to silo B. Silo A then feeds material to dry stirred mill I. The above process is repeated multiple times until the material being ground meets the grinding requirements and the grinding process is completed. This invention uses a method of multiple grinding, multiple cooling, and multiple gas-solid separation to avoid the material being heated for too long in the mill and the temperature being too high, thus avoiding the failure of grinding aids. This allows the grinding process to proceed smoothly, improves grinding efficiency, and accelerates the grinding speed. It breaks through the limitation that effective dry pulverization is difficult to break through the 3-micron limit, achieving dry grinding of submicron and nano-particles in a single-particle state without agglomeration, which is beneficial for subsequent processing and application. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0017] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of the present invention.

[0018] Figure 4 This is a micrograph of the submicron powder after grinding according to the present invention.

[0019] Figure 5 This is a particle size detection report for the submicron powder after grinding according to the present invention.

[0020] Figure 6 These are images of a prototype that has undergone numerous trials and improvements.

[0021] In the diagram: 1. Dry stirred mill I; 2. Dry stirred mill II; 3. Conveying and cooling pipeline; 4. Gas-solid separation equipment I; 5. Fan A; 6. Silo A; 7. Silo B; 8. Feeder I; 9. Feeder II; 10. Conveyor I; 11. Conveying pipeline I; 12. Conveyor II; 13. Conveying pipeline II; 14. Gas-solid separation equipment II; 15. Fan B; 16. Classifier; 17. Silo C; 18. Feeder III. Detailed Implementation

[0022] The embodiments of the present invention will be described in conjunction with the accompanying drawings:

[0023] Example 1: As Figure 1 As shown, a method for grinding materials using a dry stirred mill is provided, comprising two silos, namely silo A6 and silo B7. The material to be ground is fed from silo A6 into the dry stirred mill I1 via feeder I8 for grinding. The ground material is cooled and conveyed, and the cooled material is then sent to a gas-solid separation device I4 via conveyor I10 for gas-solid separation. The solid obtained after gas-solid separation is sent into silo B6. The conveyor I10 is a bidirectional screw conveyor. When all the material to be ground in silo A6 has entered the dry stirred mill I1, the feeder I8 in silo A6 is turned off. Stop feeding material into dry stirred mill I. The solid obtained after gas-solid separation stops entering silo B7 and is sent to silo A6. Open feeder II9 on silo B7 to start feeding material into dry stirred mill I1. Continue until all the material to be ground in silo B7 has entered dry stirred mill I1. Close feeder II9 on silo B7. Silo B7 stops feeding material into dry stirred mill I1. The solid obtained after gas-solid separation stops entering silo A6 and is sent to silo B. Open feeder I8 on silo A6. Silo A6 starts feeding material into dry stirred mill I1. Repeat the above process multiple times until the material to be ground meets the grinding requirements and the grinding process is completed.

[0024] A conveying and cooling pipeline 3 is provided between the dry stirred mill I1 and the gas-solid separation device I4 for cooling and conveying the ground material; the conveying and cooling pipeline 3 provides cooling gas for cooling and conveying the ground material through a cooling fan 5.

[0025] The cooling gas is air, nitrogen, or argon.

[0026] The grinding media in the dry stirred mill I1 has a particle size of 3-8mm and can be made of wear-resistant materials such as alloy steel, cemented carbide, and ceramics.

[0027] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention. The main structure of this embodiment is the same as that of Embodiment 1. In this embodiment, the discharge end of the dry stirring mill I is equipped with a classifier to classify the material that has been ground multiple times and remove large particles. It is suitable for use when the particle size requirements of the product are more stringent. The qualified fine particles enter the gas-solid separation equipment II14 through the conveying pipe II13 for collection. The fan B15 provides the power for classification and exhausts the gas after gas-solid separation.

[0028] Figure 3This is a schematic diagram of the structure of Embodiment 3 of the present invention. The main structure of this embodiment is the same as that of Embodiment 1. When the material after being ground by the dry stirred mill I exhibits agglomeration: the material after being ground multiple times by the dry stirred mill I is then fed into silo C. A dry stirred mill II is installed in silo C to disperse the particle agglomerates in the material after being ground multiple times by the dry stirred mill I. A classifier is connected to the outlet of the dry stirred mill II. The classifier separates the fine particles into the product, while the coarse particles are returned to the dry stirred mill I for further grinding.

[0029] To better disperse agglomerates, the dry stirred mill II uses a grinding medium of 30-500 micrometers and an impeller edge rotation speed of 10-20 m / s.

[0030] This embodiment includes three silos: silo A6, silo B7, and silo C17. The operation of silos A6 and B7 is the same as in embodiment 1, and will not be described in detail here. After multiple grinding processes, the material containing particulate agglomerates is separated by gas-solid separation device I4. The resulting solid material enters silo C7. Then, the feeder III18 on silo C7 is turned on, and the material containing particulate agglomerates enters dry stirred mill II2. The dry stirred mill II2 disperses the particulate agglomerates, and the dispersed material enters classifier 16 for particle sieving. Selected, qualified fine particles that meet product requirements are collected in gas-solid separation equipment II14 through conveying pipe II13. The fan B15 provides the power for grading and exhausts the gas after gas-solid separation. Larger particles are sent to dry stirred mill I1 for grinding. The dry stirred mill I1 cools and conveys the ground material, and the cooled material is sent to gas-solid separation equipment I4 through conveyor I10 for gas-solid separation. The solid obtained after gas-solid separation is sent to silo A6 or silo B7. The above process is repeated until the ground product meets the requirements.

[0031] Dry stirred mill I uses a larger diameter grinding media and a lower grinding speed, which is beneficial for grinding large particles and reducing the heat generated during grinding; dry stirred mill II uses a smaller diameter grinding media and a higher grinding speed, which is beneficial for dispersing fine particles and reducing the possibility of agglomeration.

Claims

1. A method for grinding materials using a dry stirred mill, characterized in that: At least two silos are set up, namely silo A and silo B. The material to be ground is fed from the first silo, silo A, into the dry stirred mill I via a feeder for grinding. The ground material is cooled and conveyed, and then sent to a gas-solid separation device for gas-solid separation. The solid obtained after gas-solid separation is sent to the second silo, silo B. When all the material to be ground in silo A has entered the dry stirred mill I, silo A stops feeding into the dry stirred mill I. The solid obtained after gas-solid separation stops entering silo B and is sent into silo A. Silo B then feeds into the dry stirred mill I. When all the material to be ground in silo B has entered the dry stirred mill I, silo B stops feeding into the dry stirred mill I. The solid obtained after gas-solid separation stops entering silo A and is sent into silo B. Silo A then starts feeding into the dry stirred mill I. This process is repeated multiple times until the material to be ground meets the grinding requirements and the grinding process is completed.

2. The method for grinding materials using a dry stirred mill as described in claim 1, characterized in that: A conveying and cooling pipeline is provided between the dry stirred mill I and the gas-solid separation equipment for cooling and conveying the ground material; the conveying and cooling pipeline provides cooling gas for cooling and conveying the ground material through a cooling fan.

3. The method for grinding materials using a dry stirred mill as described in claim 1, characterized in that: The grinding media in the dry stirred mill I has a particle size of 3-8 mm.

4. A method for grinding materials using a dry stirred mill as described in claim 1, characterized in that: The dry stirred mill I is equipped with a classifier at the discharge end to classify the material that has undergone multiple grinding processes and remove large particles.

5. A method for grinding materials using a dry stirred mill as described in claim 1, characterized in that: After being ground multiple times by the dry stirred mill I, the material enters the silo C. A dry stirred mill II is installed in the silo C to disperse the particle agglomerates in the material that has been ground multiple times by the dry stirred mill I. A classifier is connected to the outlet of the dry stirred mill II. The classifier separates the fine particles into the product, while the coarse particles are returned to the dry stirred mill I for further grinding.

6. The method for grinding materials using a dry stirred mill as described in claim 1, characterized in that: To better disperse agglomerates, the dry stirred mill II uses a grinding medium of 30-500 micrometers and an impeller edge rotation speed of 10-20 m / s.

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