Hyperfine wet grinding system

Abstract

The hyperfine wet grinding system comprises a grinding machine, two grinding tanks, a coarse material tank, an intermediate tank, a hydrocyclone, an overflow collecting tank, an underflow collecting tank and a pipeline ultrasonic device, the discharging ends of the two grinding tanks and the coarse material tank are converged through a first pipeline and then are connected with the feeding end of the grinding machine; the intermediate tank is connected with the discharging end of the grinding machine through a second pipeline; the pipeline ultrasonic device is connected to the second pipeline in series; the discharging end of the intermediate tank is connected with the hydrocyclone through a third pipeline, and the third pipeline is connected with a cyclone pump in series; an overflow port of the hydrocyclone is connected with the overflow collecting tank through a fourth pipeline, an underflow discharge port of the hydrocyclone is opposite to the underflow collecting tank, and a discharge port of the underflow collecting tank is connected with the coarse material tank through a fifth pipeline; the outlet end of the overflow collecting tank is connected with the two grinding tanks through a sixth pipeline; the system overcomes the problems of non-uniform grinding and excessive grinding in the prior art. The grinding method is simple in step, convenient to operate and capable of achieving continuous automation.

Description

Technical Field

[0001] The utility model relates to an ultra-fine wet grinding system. Background Art

[0002] Micro-nano materials have unique physical, chemical and electrical properties and are widely used in energy, electronics, medicine and materials science. However, the original micro-nano materials often have large particle size and uneven distribution, which limits their performance and effect in applications. Therefore, it is of great significance to achieve the refinement, homogenization and functionalization of micro-nano materials by grinding.

[0003] Stirred mills and sand mills are key equipment for achieving fine material processing in powder industry production. They have been applied to many fields such as coatings, medicine, and chemicals, significantly improving the ultra-fine dispersion effect of powders, and greatly improving product quality and process levels. In general, if you want to get a finer particle size, it is mainly achieved by increasing the grinding time and increasing the grinding speed. However, too long grinding time may lead to over-grinding and particle aggregation, while too short grinding time may not achieve the required particle size and uniformity. Higher grinding speeds can increase collision and shear forces, which is conducive to the rapid reduction of particle size, but too high a speed can cause material overheating and inactivation, and there is a risk of particle breakage and morphology change.

[0004] With the rapid development of materials science and its downstream application technology, the demand for nano-level grinding of advanced materials is becoming more and more high-end and refined. Improving the ultra-fine dispersion effect and efficiency plays an important role in improving the quality of powder materials in various fields. When nanomaterials are used, there are strict range requirements for particle size distribution. The smaller the particles, the better. At the same time, there are higher requirements for particle integrity. If high-intensity grinding is used, the maximum particle size D 100 Although it will decrease, the median particle size D 50 At the same time, it will also become smaller sharply and exceed the qualified range. In addition, long-term and high-intensity grinding will not only introduce zirconium element pollution, but also seriously damage the morphology of the particles and affect the application performance of the powder material. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide an ultra-fine wet grinding system, which applies a grading device and an ultrasonic device to the grinding system, thereby overcoming the problems of uneven grinding and over-grinding in the prior art.

[0006] In order to solve the above technical problems, an ultra-fine wet grinding system is provided, comprising a grinder, two grinding tanks arranged in parallel, a coarse material tank, an intermediate tank, a hydrocyclone, an overflow collecting tank, an underflow collecting tank, and a pipeline ultrasonicator; the discharge ends of the two grinding tanks and the coarse material tank are connected to the feed end of the grinder after being converged through a first pipeline; the intermediate tank is connected to the discharge end of the grinder through a second pipeline; the pipeline ultrasonicator is connected in series to the second pipeline; the discharge end of the intermediate tank is connected to the hydrocyclone through a third pipeline, and a cyclone pump is connected in series to the third pipeline; the overflow port of the hydrocyclone is connected to the overflow collecting tank through a fourth pipeline, the underflow discharge port of the hydrocyclone is directly opposite to the feed port of the underflow collecting tank, and the discharge port of the underflow collecting tank is connected to the coarse material tank through a fifth pipeline; the outlet end of the overflow collecting tank is connected to the two grinding tanks through a sixth pipeline;

[0007] The grinding tank, the coarse material tank and the intermediate tank are all provided with stirring paddles inside the tank bodies, and the outer walls of the tank bodies are all provided with cooling water interlayers, and the volume of the intermediate tank is not less than that of the grinding tank; the inner walls of the coarse material tank and the underflow collecting tank are also provided with ultrasonic oscillators;

[0008] Valves are provided at the bottoms of the two grinding tanks and the coarse material tank corresponding to the positions of the first pipeline.

[0009] Preferably, the grinder is a vertical stirred mill or a horizontal sand mill suitable for a wet grinding process; the grinding media filled in the grinder are zirconium oxide balls or silicon carbide balls, or cerium oxide balls.

[0010] Preferably, the hydrocyclone is made of polyurethane or polypropylene.

[0011] Preferably, the hydrocyclone is installed at the highest point of the system, and a pressure gauge and a flow meter are installed on the third pipeline; the fourth pipeline is allowed to have only one elbow at most, and the elbow angle is 120°-180°.

[0012] Preferably, the overflow collecting trough and the underflow collecting trough are installed at positions lower than the overflow discharge port and the underflow discharge port of the hydrocyclone, respectively.

[0013] Preferably, the pipeline ultrasonic device is composed of one or more groups of ultrasonic generators; and its ultrasonic components or probes are not in direct contact with the slurry.

[0014] Preferably, the vortex pump is a centrifugal pump.

[0015] For the purpose of simple explanation, the ultra-fine wet grinding system described in the present invention is referred to as the system below.

[0016] The grinding method of the system comprises the following steps:

[0017] (1) According to the grinding system suitable for the material, add a certain amount of water or solvent into a grinding tank and start stirring;

[0018] (2) Weigh the material to be ground and slowly add it into the grinding tank for slurry preparation, controlling the solid content of the slurry to be between 20% and 50%;

[0019] (3) Use a feed pump to transport the slurry in the grinding tank into the grinder for grinding; the grinding speed is adjusted by frequency conversion, the linear speed is 5 to 13 m / s, and the diameter of the grinding medium is 0.1 mm to 1.0 mm;

[0020] (4) The ground slurry is ultrasonically vibrated by the ultrasonic device on the second pipeline and then enters the intermediate tank;

[0021] (5) Keep the bottom valve of the intermediate tank closed. After all the slurry in the grinding tank is ground, open the valve and transfer the slurry to the hydrocyclone through the cyclone pump. The cyclone pump adopts frequency conversion control to stabilize the pressure of the third pipeline at 2.0-4.0 bar.

[0022] (6) The hydrocyclone uses the centrifugal principle for wet classification. Large particles flow out from the bottom flow outlet and are collected in the bottom flow collection tank, and small particles flow out from the upper overflow port to the overflow collection tank;

[0023] (7) Control the inlet valves of the two grinding tanks so that all the fine materials in the overflow collection tank enter the other grinding tank; the coarse materials in the underflow collection tank enter the coarse material tank after ultrasonic dispersion and continue ultrasonic dispersion;

[0024] (8) After the grinding of the slurry in the grinding tank is completed, the slurry in the coarse material tank is ground according to the above steps by controlling the valve on the first pipeline and collected in the grinding tank;

[0025] (9) After the grinding of the slurry in the coarse material tank is completed, control the valve on the pipeline and re-grind the slurry in the grinding tank according to the above steps until the target particle size is reached.

[0026] The ground material is one of barium titanate powder, zirconium oxide powder, cerium oxide powder, barium carbonate powder, titanium dioxide powder, ceramic formula powder for MLCC, and potassium titanate powder.

[0027] Advantages of this system: This system achieves the purpose of ultra-fine grinding by wet grinding the material through the method of double tank switching, ultrasonic dispersion and online classification. The classification equipment and ultrasonic equipment are applied to the common grinding system. The particles in the slurry are classified online while grinding, and the separated large particles are ground separately, which also avoids over-grinding of small particles. The particle size distribution of the ground material is narrow. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a structural diagram of this system.

[0029] Figure 2 This is a comparison of the grinding particle size distribution diagram of barium titanate powder in Example 1.

[0030] Figure 3 This is a comparison of the grinding particle size distribution diagram of titanium dioxide powder in Example 2. DETAILED DESCRIPTION

[0031] Embodiment 1:

[0032] See also Figure 1 A superfine wet grinding system comprises a grinder 1, two grinding tanks 2a and 2b arranged in parallel, a coarse material tank 2c, an intermediate tank 2d, a hydrocyclone 4, an overflow collection tank 5, an underflow collection tank 6, and a pipeline ultrasonic device 3; the discharge ends of the two grinding tanks 2a and 2b and the coarse material tank 2c are connected to the feed end of the grinder 1 after being converged through a first pipeline 10-1; the intermediate tank 2d is connected to the discharge end of the grinder 1 through a second pipeline 10-2; the pipeline ultrasonic device 3 is connected in series to the second pipeline 10-2 The discharge end of the intermediate tank 2d is connected to the hydrocyclone 4 through the third pipeline 10-3, and the cyclone pump 9 is connected in series to the third pipeline 10-3; the overflow port of the hydrocyclone 4 is connected to the overflow collecting tank 5 through the fourth pipeline 10-4, the underflow discharge port of the hydrocyclone 4 is directly opposite to the feed port of the underflow collecting tank 6, and the underflow collecting tank 6 is connected to the coarse material tank 2c through the fifth pipeline 10-5; the outlet end of the overflow collecting tank 5 is connected to the two grinding tanks 2a and 2b through the sixth pipeline 10-6;

[0033] The grinding tanks 2a, 2b, the coarse material tank 2c, and the intermediate tank 2d are all provided with stirring paddles inside the tank bodies, and the outer walls of the tank bodies are all provided with cooling water interlayers, and the volume of the intermediate tank 2d is not less than that of the grinding tanks 2a and 2b; the inner walls of the coarse material tank 2c and the underflow collecting tank 6 are also provided with ultrasonic oscillators 7;

[0034] Valves are provided at the bottoms of the two grinding tanks 2a, 2b and the coarse material tank 2c at the positions of the first pipeline 10-1.

[0035] The grinder 1 is a vertical stirred mill or a horizontal sand mill suitable for a wet grinding process; the grinding media filled in the grinder are zirconium oxide balls or silicon carbide balls or cerium oxide balls.

[0036] The hydrocyclone 4 is made of polyurethane or polypropylene.

[0037] The hydrocyclone 4 is installed at the highest point of the system. The third pipeline 10-3 is equipped with a pressure gauge and a flow meter. The fourth pipeline 10-4 is allowed to have only one elbow at most, and the elbow angle is 120°-180°.

[0038] The installation positions of the overflow collecting trough 5 and the underflow collecting trough 6 are respectively lower than the overflow discharge port and the underflow discharge port of the hydrocyclone 4 .

[0039] The pipeline ultrasonic device 3 is composed of one or more groups of ultrasonic generators; its ultrasonic components or probes are not in direct contact with the slurry.

[0040] The vortex pump 9 is a centrifugal pump.

[0041] A grinding method of an ultrafine wet grinding system comprises the following steps:

[0042] (1) At 5m 3 Add 3t of water into the grinding tank 2a and start stirring;

[0043] (2) Weigh 2 tons of barium titanate powder to be ground and slowly add it into the grinding tank 2a for slurry dispersion, with a slurry solid content of 40%;

[0044] (3) The slurry in the grinding tank 2a is transported to the grinder 1 by the feed pump 8 for grinding; the grinding speed is 350 rpm, the linear speed is 5 m / s, and the grinding medium is zirconia beads with a size of Φ0.3 mm; at this time, the particle sizes of the ground barium titanate are D 50 =1.107um, D 100 =24.536um;

[0045] (4) The ground slurry is ultrasonically vibrated by the ultrasonic device 3 on the pipeline 10-2, and then enters the 5m 3 Intermediate tank 2d; ultrasonic frequency 40KHz, ultrasonic intensity 4000W / m 2 ;

[0046] (5) Keep the bottom valve of the intermediate tank 2d in the closed state. After the slurry in the grinding tank 2a is completely ground, open the bottom valve and transport the slurry to the hydrocyclone 4 through the cyclone pump 9. The hydrocyclone 4 is made of all polyurethane material, with a rated working pressure of 3.2 bar and a working flow of 1m 3 / h, overflow removal of large particles larger than 5um;

[0047] (6) The vortex pump 9 adopts frequency conversion control to stabilize the pressure of pipeline 10-3 at 2.0 bar and the flow rate at 1m 3 / h; the coarse particles larger than 5um flowing out from the bottom discharge port are collected in the underflow collection tank 6, and the fine particles smaller than 5um flowing out from the upper overflow port are collected in the overflow collection tank 5;

[0048] (7) Control the inlet valves of grinding tanks 2a and 2b so that all the fine materials in overflow collection tank 5 enter 5m 3Grinding tank 2b; after the coarse material in the underflow collecting tank 6 is ultrasonically dispersed, it enters the coarse material tank 2c and continues ultrasonic dispersion, the ultrasonic frequency is 40KHz, the ultrasonic intensity is 4000W / m 2 ;

[0049] (8) After the slurry in the grinding tank 2a is ground, the valve on the control pipe 10-1 is controlled and the grinding is continued for 5 m 3 The slurry in the coarse material tank 2c is collected in the grinding tank 2b;

[0050] (9) After the grinding of the slurry in the coarse material tank 2c is completed, the valve on the control pipeline 10-1 is controlled to grind the slurry in the grinding tank 2b again according to the above steps until the target particle size is reached.

[0051] from Figure 2 It can be seen that the barium titanate powder treated by the utility model has a uniform particle size distribution and a narrow distribution range, and there are no large particles beyond the range. The specific value is D 50 =1.016um, D 100 =3.897um. If the hydrocyclone is not used for online classification after grinding in step (3), but the grinding speed of the grinding machine is increased to enhance the grinding shear force and impact force, D 50 The particles will suddenly become smaller, and their morphology will be destroyed, and the particles may even be split into two, affecting the performance of the material.

[0052] Embodiment 2:

[0053] A grinding method of an ultrafine wet grinding system comprises the following steps:

[0054] (1) At 5m 3 Add 3t of water into the grinding tank 2a and start stirring;

[0055] (2) Weigh 1 t of titanium dioxide powder to be ground and slowly add it into the grinding tank 2a for slurry dispersion, with a slurry solid content of 25%;

[0056] (3) The slurry in the grinding tank 2a is transported to the grinder 1 by the feed pump 8 for grinding; the grinding speed is 350 rpm, the linear speed is 5 m / s, and the grinding medium is zirconia beads with a size of Φ0.3 mm; at this time, the particle sizes of the ground titanium dioxide are D 50 =0.103um, D 100 =2.919um;

[0057] (4) The ground slurry is ultrasonically vibrated by the ultrasonic device 3 on the pipeline 10-2, and then enters the 5m 3 Intermediate tank 2d; ultrasonic frequency 40KHz, ultrasonic intensity 6000W / m 2 ;

[0058] (5) Keep the bottom valve of the intermediate tank 2d in the closed state. After the slurry in the grinding tank 2a is completely ground, open the bottom valve and transport the slurry to the hydrocyclone 4 through the cyclone pump 9. The hydrocyclone 4 is made of all polyurethane material, with a rated working pressure of 3.2 bar and a working flow of 1m 3 / h, overflow to remove large particles larger than 1um;

[0059] (6) The vortex pump 9 adopts frequency conversion control to stabilize the pressure of pipeline 10-3 at 2.0 bar and the flow rate at 1m 3 / h; the coarse particles larger than 5um flowing out from the bottom discharge port are collected in the underflow collection tank 6, and the fine particles smaller than 5um flowing out from the upper overflow port are collected in the overflow collection tank 5;

[0060] (7) Control the inlet valves of grinding tanks 2a and 2b so that all the fine materials in overflow collection tank 5 enter 5m 3 Grinding tank 2b; after the coarse material in the underflow collecting tank 6 is ultrasonically dispersed, it enters the coarse material tank 2c and continues ultrasonic dispersion, the ultrasonic frequency is 40KHz, and the ultrasonic intensity is 6000W / m 2 ;

[0061] (8) After the slurry in the grinding tank 2a is ground, the valve on the control pipe 10-1 is controlled and the grinding is continued for 5 m 3 The slurry in the coarse material tank 2c is collected in the grinding tank 2b;

[0062] (9) After the grinding of the slurry in the coarse material tank 2c is completed, the valve on the control pipeline 10-1 is controlled to grind the slurry in the grinding tank 2b again according to the above steps until the target particle size is reached.

[0063] from Figure 3 It can be seen that the particle size distribution of titanium dioxide powder treated by the utility model is uniform and the distribution range is narrow. The specific value is D 50 =0.099um, D 100 =0.255um. If the hydrocyclone is not used for online classification after grinding in step (3), but the grinding speed of the grinding machine is increased to enhance the grinding shear force and impact force, D 50 , D 100 The reduction speed is very slow, and there are problems such as long grinding time, low efficiency, and introduction of many zirconium impurities.

[0064] The utility model has obvious advantages in improving grinding efficiency, optimizing particle size distribution and removing large particles.

[0065] The above is only the best implementation of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the principle of the present invention, the technical solution of the present invention can be modified or replaced by equivalents, which can also achieve the technical effect of the present invention and should also be regarded as belonging to the protection scope of the present invention.

Claims

1. An ultra-fine wet grinding system, characterized in that: It comprises a grinder, two grinding tanks arranged in parallel, a coarse material tank, an intermediate tank, a hydrocyclone, an overflow collecting tank, an underflow collecting tank, and a pipeline ultrasonic device; the discharge ends of the two grinding tanks and the coarse material tank are connected to the feed end of the grinder after being converged through a first pipeline; the intermediate tank is connected to the discharge end of the grinder through a second pipeline; the pipeline ultrasonic device is connected in series to the second pipeline; the discharge end of the intermediate tank is connected to the hydrocyclone through a third pipeline, and a cyclone pump is connected in series to the third pipeline; the overflow port of the hydrocyclone is connected to the overflow collecting tank through a fourth pipeline, the underflow discharge port of the hydrocyclone is directly opposite to the feed port of the underflow collecting tank, and the discharge port of the underflow collecting tank is connected to the coarse material tank through a fifth pipeline; the outlet end of the overflow collecting tank is connected to the two grinding tanks through a sixth pipeline; The grinding tank, the coarse material tank and the intermediate tank are all provided with stirring paddles inside the tank bodies, and the outer walls of the tank bodies are all provided with cooling water interlayers, and the volume of the intermediate tank is not less than that of the grinding tank; the inner walls of the coarse material tank and the underflow collecting tank are also provided with ultrasonic oscillators; Valves are provided at the bottoms of the two grinding tanks and the coarse material tank corresponding to the positions of the first pipeline.

2. The ultrafine wet grinding system according to claim 1, characterized in that: The grinder is a vertical stirred mill or a horizontal sand mill suitable for a wet grinding process; the grinding media filled in the grinder are zirconium oxide balls or silicon carbide balls, or cerium oxide balls.

3. The ultrafine wet grinding system according to claim 1, characterized in that: The hydrocyclone is made of polyurethane or polypropylene.

4. The ultrafine wet grinding system according to claim 1, characterized in that: The hydrocyclone is installed at the highest point of the system. The third pipeline is equipped with a pressure gauge and a flow meter. The fourth pipeline is allowed to have only one elbow at most, and the elbow angle is between 120° and 180°.

5. The ultrafine wet grinding system according to claim 1, characterized in that: The installation positions of the overflow collecting trough and the underflow collecting trough are respectively lower than the overflow discharge port and the underflow discharge port of the hydrocyclone.

6. The ultrafine wet grinding system according to claim 1, characterized in that: The pipeline ultrasonic device is composed of one or more groups of ultrasonic generators; its ultrasonic components or probes are not in direct contact with the slurry.

7. The ultrafine wet grinding system according to claim 1, characterized in that: The vortex pump is a centrifugal pump.

Images