First, the structure of the jet mill
The jet mill consists of the following parts:
The main unit is the airflow crushing part.
Electromagnetic vibrating feeder and controller feed the main machine.
The collector is a cloth bag, which collects the finished product and discharges the gas.
Pressure gauges and pressure regulators: control and regulate pressure.
Installation of the bottom plate and the pipeline: The above parts are assembled on the bottom plate to form a crusher assembly.
Air compressor: Provides a pressure source to the airflow mill mainframe.
Filter: Air compressor pressure gas is filtered through a filter to remove moisture and dirt and then passed to the airflow mill main unit.
Second, the working principle of the jet mill
The strong multi-turbulent flow field formed when the high-speed airflow is sprayed causes the solid particles therein to be deformed and broken during self-collision or collision with the impact plate and the wall.
The powder is fed into the feed nozzle by the electromagnetic vibrating feeder, and is injected into the crushing chamber by the compressed air supplied by the feed, and the supersonic flow is formed by the high-speed airflow sprayed from the crushing nozzle, causing collision, shearing and crushing of the cavity in the flow. Wall collision and friction achieve the purpose of pulverizing into fine powder. During high-speed movement and pulverization of the stream, particles of different fineness will produce different centrifugal forces in the swirling airflow. The powder particles of acceptable fineness have greater force than the centripetal airflow. The centrifugal force is brought to the discharge pipe by the exhaust gas flow, and the finished product is collected through the cloth bag, and the larger particles are thrown to the periphery due to the centrifugal force greater than the force of the centripetal air flow, and the pulverization process continues with the high-speed movement of the logistics.
Third, the performance characteristics
The internal vertical grading device can adjust the particle size of the product, the pulverization granularity is good, the distribution is relatively narrow, the product fineness is uniform, the particle surface is smooth, the shape is regular, the purity is high, the activity is large, and the dispersion is good.
It is suitable for pulverizing low-melting and heat-sensitive materials and biologically active products. Because the jet mill is powered by compressed air, the adiabatic expansion of the compressed gas at the nozzle will lower the temperature of the system, so no large amount of heat will be generated during the work.
It can be used in series with a multi-stage classifier, so that multiple particle size segments can be formed simultaneously.
The equipment is easy to disassemble and easy to clean. It has no dead angle on the inner wall, can be cleaned thoroughly, and can be operated under aseptic conditions.
Closed operation, low running noise, can reduce the generation of dust, not only environmental protection, but also less contaminated products.
The production process is continuous, the production capacity is large, the degree of automation and automation is high, the control system is simple to operate, and the equipment operation is safe and reliable.
Joint operations can be implemented. Because when pulverizing with superheated high-pressure saturated steam, the material can be pulverized and dried at the same time, and can be used as a mixer; while the material is pulverized, it can be sprayed with a solution of the desired concentration to cover the solid fine particles, The coating layer is formed and surface-modified, and therefore, jet milling can be combined with pulverized surface coating and surface modification.
Fourth, classification
There are several types of jet mills in China: flat jet mill, fluidized bed jet mill, circulating tube jet mill, jet jet mill, and target jet mill.
Flat jet mill
Flat jet mill
Flat airflow mill working principle diagram
Fluidized bed jet mill
Friend equipment manufacturing fluidized bed jet mill
Weifang Zhengyuan Fluidized Bed Airflow Crusher
Circulating tube airflow pulverizer
Circulating tube airflow pulverizer
Jet jet mill
Close friend equipment manufacturing spray jet mill
Target jet mill
Target airflow mill structure schematic
Fifth, the jet mill applications in the non-gold mining industry of the genus
Airflow pulverization technology is a simple physical comminution of materials. In the pulverization, since there is no other substance doping and the process temperature is low, the original chemical properties of the material can be maintained, and the loss of the heat sensitive component in the material can be reduced. At the same time, the agglomeration of the mineral, metal and the like powder after the air flow pulverization Phenomena, dispersibility and uniformity are superior to those of traditional mechanical methods, making airflow pulverization technology an irreplaceable position in mineral processing. Especially ultrafine jet milling technology is widely used in the deep processing of titanium white powder, talc, wollastonite, kaolin, quartz, graphite, diatomaceous earth, mica, barite, bentonite and the like of non-metallic mineral. However, the design and manufacturing level of China's jet mills is still far from the developed countries.
1, talc
The raw materials of the talc ore after coarse crushing and medium crushing are transported to the jet mill for ultrafine grinding, and the milled material is the final product with a fineness of 500-5000 mesh. The main body is ultra-fine grinding into a flat airflow pulverizer.
2, wollastonite
The ultra-fine pulverization of wollastonite with flat airflow pulverizer has better selectivity than medium agitating mill, can ensure the complete crystal morphology of wollastonite, and is an effective ultrafine pulverization for preparing high aspect ratio acicular wollastonite powder. equipment.
3, kaolin
As a clay mineral for ceramics, papermaking and chemical fillers, kaolin requires high whiteness and brightness. The jet mill is one of the most commonly used ultrafine grinding equipments for kaolin. Its product size is generally 1~5μm. After pre-grinding to reduce the particle size of the mill, this mill can obtain products with an average particle size of less than 1 μm.
4, titanium dioxide
Titanium dioxide is used as a pigment and has very high requirements on particle size, particle size distribution and purity. Generally, mechanical pulverizing equipment is difficult to meet his requirements. Therefore, the airflow pulverizer is selected as the final pulverizing equipment for titanium dioxide at home and abroad. The most widely used flat airflow pulverizer.
Sixth, the problem that the airflow pulverizer should pay attention to in actual production and application
The first is the noise problem.
Both research and production practices have shown that the higher the gas flow rate, the finer the product obtained. When ultra-fine products are to be obtained, the speed of the airflow must be supersonic. Noise makes people unable to concentrate, distraction, and often leads to accidents. Due to the special structure of the jet mill itself, very strict requirements are imposed on the structural design of the muffler. At present, multi-stage cyclone separators and large dust removal equipment and auxiliary equipment such as exhaust fans are usually connected at the discharge port.
This is followed by the safety of supersonic jet mills for the manufacture of ultrafine powders.
Includes may cause respiratory pneumoconiosis and dust explosions. The particle size of the dust obtained by the supersonic jet mill is basically below 5 μm, which is the most harmful to the human body. The probability of a supersonic jet mill shredder operator suffering from pneumoconiosis occupational disease will increase significantly. At the same time, dust is scattered in the air on a large scale, and dust explosion may occur. China's Jiangsu Miyou Powder New Equipment Manufacturing Co., Ltd. is in a leading position in the anti-dust explosion of airflow pulverizers.
Seven, development trend
The development of information technology, biotechnology and new material technologies puts higher demands on the particle size, purity and particle size distribution of powder products, and saves energy and reduces environmental pollution as much as possible. In order to meet the needs of social production, ultra-fine pulverization technology faces severe challenges. In recent years, great progress has been made in the basic theoretical research of airflow pulverization. However, many aspects need to be improved:
Experimental research on the supersonic pulverization flow field needs to be strengthened. The high pulverization speed brings great difficulty to the direct measurement of the flow field, so the research of the test instrument should be strengthened.
At present, there are few pulverizing equipments using steam as a working medium, so that there is little research on the influence process of steam on the pulverizer, and the advantages of the steam working medium can be fully utilized to realize the enlargement of the pulverizing equipment.
In the establishment of the airflow pulverization parameter optimization model, it is still lacking, which brings difficulties to the perfection and optimization design of the pulverizing equipment.
Deepening mixing, drying, granulation, coating and other processes are combined with pulverization. The pulverization of soft materials is a major problem and research focus of the pulverization technology. Therefore, in order to meet the development needs of modern industry, it is extremely urgent to strengthen basic theoretical research and optimize equipment design.
Eight, airflow mill related companies (in no particular order)
Jiangsu Miyou Powder New Equipment Manufacturing Co., Ltd.
Weifang Zhengyuan Powder Engineering Equipment Co., Ltd.
Kunshan Qiangwei Powder Equipment Co., Ltd.
Shenyang Aircraft Research Institute Powder Company
Anqiu Longxiang Machinery Co., Ltd.
Shandong Dinkun Machinery Co., Ltd.
Yixing Hongda General Equipment Co., Ltd.
Shanghai Huasan Powder Equipment Co., Ltd.
Yixing Youte Powder Machinery Equipment Co., Ltd.
Qingdao Derui Powder Technology Equipment Co., Ltd.
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