Continuous improvement of supersonic jet mill to meet higher requirements
When the compressed gas passes through the feeding ejector, the crushed raw materials enter the crushing chamber. There are multiple crushing nozzles around the crushing chamber, which spray supersonic airflow, so that the materials are impacted by the high-speed airflow and the materials collide with each other to be crushed. The grading wheel separates the particles that meet the particle size, and the coarse particles are circulated back to the pulverizing chamber to continue pulverization. After the internal closed-circuit pulverization, a uniformly distributed ultra-fine powder can be obtained at the discharge port.
1. Suitable for dry ultra-micro process. Due to the high impact speed, up to 2.5 Mach or more, particles of 1-10 microns (μm) can be easily obtained under normal circumstances, and particles smaller than 1 micron (μm) can also be obtained according to the nature of the material.
2. Since the pulverizer has a closed-circuit classification mechanism, the coarse particles in the product are continuously circulated and pulverized, so products with uniform particles and small particle size distribution can be obtained.
3. The equipment has the advantages of short crushing time, simple structure, convenient operation and maintenance, small footprint, low noise (72dB) and no vibration.
4. High crushing efficiency, continuous crushing can be carried out, and the purity of crushed products can be maintained.
5. The introduction of the latest German technology, after years of accumulated technical experience, the comprehensive performance of the equipment has been equivalent to the same model imported from Germany and Japan;
6. It is suitable for crushing, disintegrating, spheroidizing and shaping various powders with Mohs hardness below 10;
7. After crushing, the fineness of the material can be adjusted between 3~150μm, and the D50 value of some materials can reach 1.5μm;
8. Because of its special non-medium spray crushing, it is especially suitable for ultrafine crushing of high-purity materials;
9. No heat is generated during the crushing process, which has an excellent crushing effect on heat-sensitive materials;
10. Wear-resistant protection: A variety of wear-resistant protection materials can be selected for the inside of the equipment and the grading wheel, such as alumina, zirconia, and organic materials;
11. Environmental protection and automation design, the system is closed to run without dust leakage, touch screen and PLC automatic monitoring equipment can be selected;
12. Multi-purpose design: it can be used in series with air classifiers, universal pulverizers, etc., to better meet the powder particle size requirements;
13. Application fields: chemicals, minerals, traditional Chinese medicine, cosmetics, food, flame retardants, printing toners, activated carbon, resins, etc.;
The supersonic jet mill has the effect of impact shearing on the material and the impact, friction and shearing of the material and other parts to crush the material. Therefore, the average particle size of the material after airflow pulverization is fine, the particle size distribution is narrow, the particle surface is smooth, the particle shape is regular, the purity is high, the activity is high, and the dispersibility is good; it can crush low melting point and heat-sensitive materials and biologically active products (because the airflow The machine is powered by compressed air, and the adiabatic expansion of the compressed gas at the nozzle will reduce the temperature of the system). According to statistics, about 25% of international jet mills are used for ultra-fine preparation.
In recent years, the crushing equipment has been greatly improved on the basis of the previous supersonic crusher, its structure has been continuously improved, and the crushing performance has been continuously improved. In order to meet the higher requirements of the development of information technology, biotechnology and new material technology on the particle size, purity and particle size distribution of powder products, the research of ultrafine jet pulverization technology should focus on the development of the following aspects: To improve and optimize ultra-fine jet pulverization equipment, develop new equipment, and pay attention to the matching design of pulverization and classification systems.
Jet mill can accurately control the particle size of ternary materials
One of the important quality indicators of ternary materials is particle size and particle size distribution. Particle size and particle size distribution will affect the specific surface area, tap density, compaction density, processing performance and point chemical properties of the ternary material. Ternary materials used in lithium-ion batteries need to strictly control the particle size and particle size distribution. In the processing of ternary materials, jet mills are usually used for pulverization.
The ternary material jet pulverizer uses high-speed airflow as the power and carrier, and the airflow bundle formed by compressed air is transformed into velocity energy through the nozzle in the pulverizing chamber. The specific performance is: after the compressed air is frozen, filtered, and dried, it forms a supersonic airflow through the nozzles and is injected into the crushing chamber to fluidize the material. The accelerated material merges at the intersection of the jet airflows of several nozzles, resulting in violent Collision, friction, shearing to achieve ultra-fine crushing of particles. The crushed material is transported to the impeller classification area by the rising airflow. Under the action of the centrifugal force of the classification wheel and the suction force of the fan, the coarse and fine powder are separated. The coarse powder returns to the crushing chamber according to its own gravity and continues to be crushed. The airflow enters the cyclone collector, the fine dust is collected by the bag filter, and the purified gas is discharged by the induced draft fan.
The ternary material jet mill is based on the design of the traditional fluidized bed mill and combined with the self-splitting classification technology, so that its performance is far superior to the traditional fluidized bed jet mill. Its main advantages are:
1. Low energy consumption, compared with the traditional fluidized bed jet mill, it can save energy by 30%.
2. Built-in self-distributing micro-powder classifier, the particle size distribution is concentrated, and there is no excessively large particles in the finished product.
3. The equipment has a compact structure and a small footprint.
4. There is no stock in the crushing box, no dead corners, easy to disassemble, wash, disinfect, easy to change varieties, and meet GMP requirements.
5. Low-temperature pulverization without medium, especially suitable for pulverization of low melting point, heat sensitive, sugar-containing and volatile materials.
6. For flammable and explosive materials, inert gas can be used as the medium to realize fully enclosed crushing. The inert gas is recycled and the loss is extremely low.
7. The crushing particle size range is wide, and the particle size of the finished product can be adjusted in the range of 3～180μm; the model is full, and the output of 5～3000kg/h is optional.
8. Negative pressure production, no dust pollution, and excellent environment.
9. High degree of automation, strong stability and easy operation.
In addition to ternary materials, jet mills can also be used in chemical, mining, abrasives, refractory materials, battery materials, metallurgy, building materials, pharmaceuticals, ceramics, food, pesticides, feed, new materials, environmental protection and other industries and various dry powders Superfine crushing, breaking and particle shaping of similar materials.
Jet mills are used in low temperature environment, food health care, abrasive refractory, etc.
Jet mill is a process where compressed air is accelerated by Laval nozzles into supersonic airflow and then injected into the crushing zone to fluidize the material (the airflow expands into a fluidized bed to suspend and boil and collide with each other), so every particle has the same state of motion .
- Low temperature applications
The jet mill can be operated under supersonic airflow, and a low temperature environment of tens of degrees below zero is formed in the crushing chamber. It can perform ultra-fine processing of heat-sensitive substances and plastic materials without cooling with liquid nitrogen. The production cost is low and the benefit is high. Typical materials are: pigments, resins, sulfur, molybdenum disulfide, insecticides, epoxy resins, polytetrafluoroethylene, rubber, ferrophosphorus.
- Food and health products
The stainless steel type (304) jet mill can be used in the ultra-fine processing of medicine, food and health care products. Its low-temperature pulverization, high-purity operation and processing, high smoothness, and easy cleaning of the machine make the stainless steel jet mill become a pharmaceutical, health care product and The ideal crushing equipment for the food industry not only improves the bioavailability and curative effect of drugs, but also reduces production costs. Typical products are: soybeans, pollen, hawthorn, sodium chloride, cordyceps, shiitake mushrooms, pearl powder, stomach medicine, nimodipine, antibiotics, ginseng, contrast medicine, ganoderma, gallnut, fleeceflower, etc.
- Abrasive refractory
Jet mill can ultra-fine processing of hard materials with Mohs hardness above seven. The application of fluidized bed pulverization and vertical turbine classifier makes the equipment wear extremely small. The rotating speed of the grading wheel can be adjusted, and the crushing parameters can be optimized. The combination of multiple classifiers can complete narrow-band classification of several particle sizes at one time. Typical products include: garnet, silicon dioxide, diamond, silicon carbide, white carbon black, emery, bauxite, boron carbide, tungsten carbide, special ceramics, etc.
Titanium dioxide is processed by a flat airflow ultrafine grinder to improve dispersibility
After calcination or surface treatment, all titanium dioxide powders are aggregates or sintered products of different sizes. They must be grinded to the original basic raw material size (approximately 0.15~0.35μm) in order to fully reflect its optical properties and pigment performance. Titanium dioxide is a superior white pigment. It has very high requirements on particle size, particle size distribution and purity. It is difficult for general mechanical grinding equipment to meet the requirements. Therefore, airflow ultrafine pulverizers are used as the final pulverization of titanium dioxide at home and abroad. equipment.
As an important equipment for ultrafine pulverization, the airflow superfine pulverizer plays an irreplaceable important role in the production of titanium dioxide. At present, titanium dioxide manufacturers mostly use flat airflow ultrafine pulverizers, and their working principles and application characteristics are as follows.
The working principle of the flat airflow ultrafine pulverizer: the material to be pulverized is injected into the pulverizing chamber through the nozzle, and the high-pressure airflow enters the air distribution chamber through the inlet. The distribution chamber is connected with the pulverizing chamber. At a speed of several hundred meters to thousands of meters per second, because the grinding nozzle and the grinding chamber form an acute angle (grinding angle), the grinded material rotates under the drive of the high-speed swirling flow. Between the particles, the particles and the body produce mutual impact, collision and friction and grind. The fine powder is guided by the centripetal airflow into the center outlet pipe of the grinder and enters the collector for collection, and the materials that do not meet the requirements are returned to the grinding chamber to continue grinding until it reaches the required fineness and is collected.
The flat airflow ultra-fine pulverizer used for the pulverization of titanium dioxide has the following advantages:
1. Due to the self-grading function, the product particle size distribution can be controlled in a very narrow range by adjusting the parameters;
2. No mechanical rotating parts, less pollution to the product;
3. Superheated steam can be used as the pulverizing working medium, with low viscosity and no static electricity, which can reduce the secondary cohesion of the powdered material;
4. Grindingunder high temperature conditions can improve the application dispersibility of titanium dioxide and increase the fluidity of titanium dioxide;
5. The flat airflow ultrafine pulverizer can add organic additives while pulverizing to modify the surface, which can increase the dispersibility of titanium dioxide in different application systems.
Laboratory ultra-fine jet mill is more suitable for processing high value-added materials
The laboratory ultra-fine jet mill has the characteristics of small size, convenient operation, high crushing precision and stable performance. Although the laboratory ultrafine jet mill can be used for dry pulverization of a variety of materials, it is more suitable for high value-added materials in view of its relatively high cost and required energy consumption.
So, what materials are the laboratory ultrafine jet mills suitable for? Let us first talk about the advantages of the laboratory ultrafine jet mill.
1. The jet mill is where the materials collide with each other for crushing, and the products are free of iron pollution and can completely reach the food safety level.
2. It does not need to be washed with water or water, and it is produced completely by dry method, and the fine powder with better particle size distribution can be obtained after one-time production.
3. The stable and complete classification flow field and special sealing measures reliably prevent the leakage of coarse particles, with a narrow particle size distribution and no large particles.
4. The jet pulverizing classifier has a variable combined structure: one machine has two functions, which can be smashed and classified separately.
5. Wear-resistant treatments are used for the parts that are easy to wear, which greatly reduces the wear of the equipment and prolongs the service life. Automatic control, low noise, no dust pollution.
The laboratory ultrafine jet mill is more suitable for the following materials:
1. Battery materials: lithium cobalt oxide, cobalt oxide, lithium manganese oxide, manganese dioxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium carbonate, lithium iron phosphate, ternary materials, natural graphite, artificial graphite, pitch rock, Lithium hydroxide, cobalt tetroxide, ferrous oxalate, iron phosphate, carbon powder, etc.
2. High hardness materials: silicon carbide, various corundum, boron carbide, alumina, zirconia, garnet, zircon sand, diamond, etc.
3. Non-metallic minerals: quartz, graphite, kaolin, calcium carbide, mica, barite, mullite, medical stone, wollastonite, talc, pyrophyllite, etc.
4. Chemical industry: aluminum hydroxide, catalysts, various dyes, epoxy resins, various additives, etc.
5. Other materials: ceramic materials, refractory materials, electronic materials, magnetic materials, rare earth materials, phosphors, copy material powder, etc.
Jet mill is an indispensable equipment in the preparation of lithium cobalt oxide
In lithium-ion batteries, the cathode material is the most important component, and it is also the key to determining the performance of lithium-ion batteries. Lithium cobaltate, lithium vanadium phosphate and lithium iron phosphate have been widely used as cathode materials. Among them, lithium cobalt oxide has an average output voltage of 3.7V, an energy density of up to 140mAh/g, and has the advantages of good cycle performance and thermal stability. These advantages make lithium cobalt oxide considered the most potential high-voltage battery cathode material. The preparation and processing of lithium cobalt oxide powder is also related to the quality of subsequent products, so in the preparation of lithium cobalt oxide, the selection of ultra-fine grinding and classification equipment is particularly important.
Ultra-fine grinding and classification is an indispensable item for lithium cobalt oxide processing, and it is also the back-end equipment of all processing procedures, which has an important effect on the quality of the finished lithium cobalt oxide powder. For the ultra-fine pulverization and classification of lithium cobalt oxide, a jet mill is usually used to make the processed finished product have the characteristics of fine particle size, uniform particle size distribution, good dispersibility, and pollution-free.
Equipment characteristics of lithium cobalt oxide jet mill:
- It has the ability of shaping, and can control the particle morphology and particle size. The finished product has excellent particle morphology and can be used for shaping of different material characteristics and requirements.
- The particle size distribution is narrow, and the finished product has a high tap density.
- Over-grinding is low, and the finished product rate can reach over 96%.
- The equipment is lined with wear-resistant materials, the equipment wears little, and the finished product has high purity.
- Using frequency converter for precise control, the material fineness can be adjusted arbitrarily between 0.5-100 μm.
- Full negative pressure operation, low noise, no dust pollution.
Lithium cobalt oxide jet mill is also suitable for lithium battery cathode materials: iron phosphate, lithium iron phosphate, ternary materials, lithium manganate, lithium nickel manganate, lithium carbonate, lithium hydroxide, ferrous oxalate and other dry powder materials Crushing, breaking and particle shaping.
Jet mill is suitable for crushing flammable, explosive and oxidizing materials
Jet mills are popular in the pulverization of various industries. In order to obtain finer and more concentrated powders, more and more manufacturers choose jet mills to pulverize materials. Typical materials crushed by jet mill are: superhard diamond, silicon carbide, metal powder, etc., high purity requirements: ceramics, pharmaceuticals, biochemistry, etc., low temperature requirements: pharmaceuticals, pvc. By changing the ordinary air of the gas source to inert gases such as nitrogen and carbon dioxide, this machine can be used as an inert gas protection device, suitable for the crushing and classification of flammable, explosive and oxidizing materials.
The materials enter the jet mill from the feed port, and the materials squeeze and collide in the middle of the crushing chamber driven by the air flow. The classifier classifies qualified materials and enters the cyclone collector. The finer tailings are transported to the bag filter by airflow. After filtering through a cloth bag, the tailings enter the outlet of the lower part of the dust collector, and the pure air is emptied. The main engine has no engine parts, no engine and any other transmissions. The high-pressure air generated by the air compressor is released into the main engine through the jet nozzle of the mill. There is no traditional grinding media, such as "milling ring", "milling ball", "grinding rail" and other grinding media. Driven by high-pressure air, they collide with each other inside the crusher to achieve the purpose of crushing. There is no traditional long time pressure and friction in the whole crushing process, the material is crushed by its own collision force, and the crushing process does not contact the material of the equipment.
Jet mill is suitable for the crushing of high hardness, high purity, heat sensitive materials, and there is no problem of traditional equipment wear. The main cause of bearing overheating and damage is too much oil, too little or aging. Therefore, according to the quantitative use of lubricating oil, generally lubricating the space of the bearing from 50% to 70%, too much or too little is not conducive to bearing lubrication and heat transfer, and prolongs the service life of the bearing. The supporting bearing cap is fastened to the shaft. If the bearing and shaft are too tight or too loose, the bearing will overheat.
The ultrafine powder produced by jet mill has safety problems such as respiratory tract pneumoconiosis and dust explosion. The particle size of the dust produced by jet mill is basically below 5μm, and the dust below 5μm is harmful to the human body. At the same time, when dust is dispersed in the air to form a dust cloud, a dust explosion may occur. Because the dust particles are not captured during the pulverization process of the jet mill, they have an appropriate particle size and distribution: the general particle size is less than 5μm, the dispersion stability in the air is good, and the explosion limit is easily reached. The consequences of a dust explosion are extremely serious.
The laboratory special crushing classifier is suitable for a variety of materials, and the fineness is adjustable
The laboratory special crushing classifier adopts high-speed impact crushing, which is suitable for a variety of materials and has a wide range of uses. It can pulverize calcium carbonate and other non-metallic mineral powders, fibrous materials such as wood powder, and chemical raw materials such as zinc stearate.
The general crushing classifier is just imitating the principle of the industrial crusher to simplify, and the fineness is generally only about 200 meshes; while the laboratory-specific crushing classifier is fully scaled down according to the impact crusher production line, with high precision and functions. The fineness is the same as the industrial pulverizer, adapting to a variety of materials, the fineness can be adjusted arbitrarily, and the fineness can reach 800 meshes.
Features of special crushing classifier for laboratory:
1. The laboratory-specific crushing classifier is used in laboratory small batch processing, and the small feeding amount of the laboratory-specific crushing classifier is about 200g;
2. The granularity of crushing and classification can be adjusted arbitrarily from D50:1~45μm;
3. Frequency conversion control, stable fineness and continuous work;
4. Quick installation connection, easy to disassemble, easy to clean, no dead corners;
5. The special crushing classifier in the laboratory does not heat up during the crushing process, no impurities are mixed, and the noise is low;
6. The laboratory special crushing classifier has a small footprint and beautiful appearance;
7. Good sealing, no dust, and small loss;
8. The special crushing classifier for the laboratory can flexibly realize the integration of airflow crushing, airflow classification and mechanical crushing;
9. The rotor of the horizontal classifier can reach 18,000 rpm;
10. The mobile mechanical crusher unit is extremely convenient to disassemble and assemble;
11. The mechanical pulverizer can realize full ceramicization;
12. The laboratory special crushing classifier can realize the inert gas circulating atmosphere and the powder classification of flammable and explosive materials;
The crushing mechanism of the laboratory-specific crushing classifier determines its wide application range and high fineness of the finished product. Typical materials include: superhard diamond, silicon carbide, metal powder, etc., high-purity requirements: ceramic pigments, medicine, Biochemical, etc., low temperature requirements: medicine, PVC. By changing the ordinary air in the air source into inert gases such as nitrogen and carbon dioxide, the laboratory-specific crushing classifier can be used as an inert gas protection device, which is suitable for the crushing and classification of flammable, explosive, and oxidizable materials.
The difference between fluidized bed jet mill and flat jet mill
The fluidized bed jet mill is named because the material is in a fluidized state during the crushing process in the cavity; the disc jet mill is also called the supersonic jet mill or the flat jet mill.
The main differences between fluidized bed jet mill and disc jet mill are as follows:
1. The difference in crushing methods
The fluidized bed jet mill is driven by high-pressure airflow to achieve crushing by the material itself at the intersection of 4 or 3 nozzles. Because it does not collide with other materials, there is no material pollution and other phenomena. At the same time, the crushing effect is also good for materials with high hardness, and it does not affect the life of the equipment.
The disc type jet mill is the material that directly impacts the inner wall of the crushing chamber through the airflow, and the collision realizes the crushing. Therefore, the crushing process has the phenomenon of abrasion on the inner lining of the crushing chamber inner wall, and the material may be contaminated. At the same time, the lining needs to be regularly Replacement, the cost of spare parts is higher.
2. The nozzle arrangement is different
The nozzle of the fluidized bed jet mill is perpendicular to the pulverizing cavity, and the pulverizing nozzle of the disc jet mill is tangent to the pulverizing chamber.
3. The way to control the granularity is different
The fluidized bed jet mill controls the particle size by adjusting the high-speed rotation speed of the grading wheel, and the particle size accuracy is well controlled; while the disc jet mill is only adjusted by adjusting the feeding speed, and the particle size is not easy to control.
4. The system wind pressure is different
The entire pulverization process of the fluidized bed jet mill is a negative pressure process, and the induced draft fan behind the system needs a high-pressure type. The entire pulverization process has no dust leakage and does not pollute the production environment. The disc-type jet mill is a positive pressure type, which does not require high induced draft fans, and even eliminates the need for induced draft fans and dust collectors. The crushing process is likely to cause dust leakage and the production environment is easily polluted.
5. The control cabinet has different methods and different costs
Because the fluidized bed jet mill controls the particle size by adjusting the high-speed rotation of the classification wheel, it needs a frequency converter to control it, so the cost is relatively high. The disc jet mill does not have high control requirements, but controls other systems such as discharge valves or dust collectors, and the relative cost is also very low.
6. The particle size distribution of the finished product is different
Compared with the flat jet mill, the fluidized bed jet mill has a narrower particle size distribution and better particle size uniformity.
Application of ultrafine jet mill in the processing of lithium manganate materials
Lithium manganate battery has the characteristics of high working voltage, light weight, small size, large specific energy, long cycle life, low self-discharge, good safety, low price, and pollution-free. It is now widely used in power tools, electric vehicles, and electric vehicles. Toys and other fields.
With the acceleration of new energy vehicles and the further improvement of lithium manganate battery technology, lithium manganate batteries, as power batteries for pure electric vehicles, have a very broad market prospect. As the back end of the lithium manganate processing procedure, the pulverization and classification have an important effect. The process of pulverizing the lithium manganate to fine particle size and separating the required particle segments directly affects the subsequent application of the lithium manganate. The ultra-fine jet mill is used for the crushing and classification of lithium manganate, which has more advantages than traditional equipment.
Ultra-fine jet mill is a kind of equipment that uses high-speed airflow to achieve ultra-fine grinding of dry materials. It consists of a crushing nozzle, a grading rotor, a screw feeder and so on. The material enters the crushing chamber through the screw feeder, and the compressed air is jetted into the crushing chamber at a high speed through a specially configured supersonic nozzle. The material is accelerated in the supersonic jet and repeatedly impacts and collides at the intersection of the nozzles to achieve crushing. The pulverized material enters the classification chamber with the ascending airflow. Due to the high-speed rotation of the grading rotor, the particles are subjected to both the centrifugal force generated by the grading rotor and the centripetal force generated by the viscous effect of the airflow. When the centrifugal force is greater than the centripetal force, the coarse particles above the grading diameter return to be crushed. The chamber continues to be impacted and crushed, and the fine particles below the classification diameter enter the cyclone separator and collector with the air flow for collection, and the gas is discharged by the induced draft fan.
Product features of superfine jet mill:
1. Precision ceramics and polyurethane lining, 100% prevent metal pollution caused by the crushing process of materials, and ensure the purity of crushed items. It is especially suitable for electronic materials that require extremely high iron content, such as lithium cobaltate, lithium manganate, lithium iron phosphate, lithium iron phosphate, ternary materials, cobalt tetroxide, lithium carbonate, lithium nickel cobaltate and other battery cathode materials.
2. No temperature rise. Because the material is crushed under the state of gas expansion, the temperature of the crushing chamber is controlled at room temperature, and the temperature will not rise.
3. The wear is small, because the main crushing effect is the impact and collision of the particles, the high-speed particles rarely collide with the wall surface, and it is suitable for crushing materials with Mohs hardness above nine.
4. Low energy consumption, 30%-40% energy saving compared with other types of jet mills.
5. The flammable and explosive materials can be crushed with inert gas protection.
6. The use of advanced touch screen and programmable logic controller (PLC) realizes automatic control.
For battery materials, according to the physical characteristics of the battery's positive and negative electrode materials, different equipment is used for pulverization and classification to achieve the best output ratio. The crushing effect can be achieved by using a special mechanical ultrafine pulverizer-grading impact mill (effectively reducing the energy consumption of production equipment); for specific materials of lithium batteries and nickel-metal hydride batteries, a fluidized bed jet mill can be used. Carry out crushing and classification. High purity requirements, anti-oxidation can use inert gas to protect the crushing classifier, isolate oxygen and close production.