Battery powder, negative electrode material gas flow grinding, has excellent plastic ability, excellent finished particle shape, can obtain ball type (potato-shaped) particles. The particle size distribution is narrow and the finished product has a high density. Mechanical ultrafine pulverizer, low pulverization, the finished product can reach 75% -95%. The inside of the device can be inner lining the wear resistant material, the finished product is purified, and the equipment is small. Airflow classifier, using variable frequency adjustment, can be adjusted between 0.5UM-100UM. The equipment is running stable, and there is no difference and variation in continuous boot for a long time. Full enclosed negative pressure, automation control, low noise, no dust pollution.In ultrafine powder technology, ultrafine powder reunion and ultrafine powder dispersion are undoubtedly a key technique. The operation of grading, granular measurement, mixing, and storage and transportation is largely dependent on the degree of dispersion of the particles.
1. Causes of ultrafine powder reunion
1. 1 Molecular action causes ultrafine powder gathering
It is well known that the molecules always exist in Van Dehua gravity, and is a short-range force. However, for the system consisting of a very large number of molecular aggregates, there is a interaction between multiple molecules, and the effective pitch of the molecular force between the particles can reach 50 nm, which belongs to the long range force. The molecular action between ultrafine powder particles is the root cause of superfine powder.
1. The electrostatic force between particles causes polygroup
Most of the particles in dry air are naturally charged. The amount of charge obtained by the particles is limited to the breakdown strength of the surrounding medium, and is about 1.7 × 10 crucible electron / cRN2 in dry air. When the charged particles are in contact with other objects, the particle surface charge is sucks the heterogeneous charge of the opposite side, so that the remaining charge is generated on the surface of the object, thereby generating a contact potential difference. 1.3 Bonding
of the particles
When the air relative humidity exceeds 65%, the water vapor begins to condense between the particles and the particles, and the particles have greatly enhanced the adhesion due to the formation of the liquid bridge. The liquid bridge bonding force is mainly composed of the adhesion caused by the capillary pressure and surface tension caused by the surface of the liquid bridge. 2 Ultrafine powder particle dispersion pathway
2.1 Surface modification
In recent years, many researchers at home and abroad use surface modification to conduct ultrafine powder dispersion research, and the surface should improve ultrafine powder. The resistance of the body particles, but due to the surface of the modified particles, it gives itThe application has a great impact, sometimes even produces great negative effects. A method of collecting nanoparticles with an organic solvent has been studied. This method can reduce the aggregation of nanoparticles in the solvent, but cannot solve the problem of ultrafine powder in the air.
2.2 Mechanical dispersion
Mechanical dispersion refers to a combination of granules to break the particles with a mechanical force, which is currently using a wide range of ultrafine powder dispersions. The necessary conditions for mechanical dispersion are mechanical (shear forces and compressive stress of fluid) should be greater than the adhesion between the particles. Typically, the mechanical force is formed by a high-speed rotating impeller or a high-speed airflow of airflow strong turbulent motion. This method is mainly to improve dispersion efficiency by improving dispersion equipment. Mechanical dispersion is more easier, but since it is a mandatory dispersion method, the mutually bonded particles can be dispersed in dispersion, but the force between the particles does not change, and the discharge of the disperser will quickly reconnect the group. Another problem with mechanical dispersion is that the brittle material may be pulverized, and the dispersed effect is lowered after the mechanical equipment is worn.
2.3 Dry Dispersion Method
In moist air, the liquid bridge formed between particles is the main cause of the particle aggregation, so that the liquid bridge produces or eliminates the formed liquid bridge is to ensure the main particle dispersion. means. In almost all of the relevant production processes are preprocessed with warm and dry to remove moisture of the material to ensure loose particles. Drying treatment is a simple and easy way. At present, the drying equipment of domestic mineral products mainly uses rotary kilns, dry pits, cylindrical dryers, electric drying boxes, far infrared dryers, etc. These devices can dry materials, but the equipment covers an area, large investment investment, low degree of automation; the operating environment is bad; equipment operation is cost effective, low heat utilization; product loss is large.
2.4 Electrostatic dispersion
Electrostatic dispersion refers to a charge between powder particles in accordance with the need for production technology, and utilizes the gulunulus between the charged particles to achieve complete and uniform dispersion between the particles. The key to electrostatic dispersion is how to make the particles fully charge. At present, the method of particle charge is mainly contact with charge, induction charge, corona charge, etc., and the particles can be charged by electron beam irradiation.
AlPA is located in the Advanced Manufacturing Industry Park, Anqiu City, Weifang City, Shandong Province, has more than 50,000 square meters of machinery production bases and modernThe management system, since its establishment, in mind the mission of "the future of powder technology to create advanced materials", adhering to the values of "compliance, and mixed parties", formulating "not seeking all, but seeking" talent strategies And cooperated with many colleges and universities to sign the "Production Research" development plan.
