Views: 205 Author: Hedy Publish Time: 2023-06-15 Origin: Site
In theory, mixing is the act of consistently combining components in any condition (solid, liquid, gas, and semi-liquid). However, the action of combining solid materials or adding a tiny quantity of liquid to solid materials is commonly referred to as mixing, while the operation of mixing solid, liquid, or gaseous components with liquid materials is referred to as stirring.So the importance of stirring in the lithium battery production process cannot be overstated. Simply said, stirring is the process of making a substance tend to be homogenous, and the material undergoes highly intricate changes during the mixing process. It is accompanied with chemical effects in addition to powerful physical impacts. Even if macroscopically attained uniformity, there are still some material particle aggregates under the microscope. Therefore, the stirring of materials is not only macroscopic homogeneity, but more importantly, microscopic relative homogeneity.
The solid-liquid suspension of the liquid is formed and sustained under mechanical stirring conditions by the mutual rotation of the stirring blade and the revolving frame, and mass transfer between the liquid and solid phases is improved. Solid-liquid mixing is often separated into three stages:(1) Solid particle suspension;(2) Re-suspension of settled particles; (3) Suspended particle penetration into liquid; (4) Use force between particles and between particles and paddles to disperse particle agglomerates or adjust particle size; and (5) Mass transfer between liquid and solid.Important Stirring Viscosity Parameters A fluid's resistance to flow. It is defined as the size of the needed shear stress on each 1cm2 plane when the liquid flows at a speed of 1cm/s, and the unit is Pa.s. A fluid's viscosity is a property. There are three states of fluid flow in a pipeline: laminar flow, transitional flow, and turbulent flow. These three flow phases also occur in stirring equipment, and the viscosity of the fluid is one of the primary criteria that determines these states.During the stirring process, any fluid with a viscosity less than 5 Pa.s is called a low-viscosity fluid, such as water, castor oil, maltose, jam, honey, lubricating oil, heavy oil, low-viscosity emulsion, and so on. A medium-viscosity fluid, such as ink or toothpaste, has a viscosity of 5-50 Pa. High-viscosity fluids with viscosities of 50-500 Pas include chewing gum, plastisol, solid fuel, and so on. Ultra-high viscosity fluids are those with a viscosity more than 500 Pa, such as rubber mixes, plastic melts, silicones, and so on.
Conventional wet process: This is the procedure utilized by 80% of businesses and is the preferred method for minor testing. Sol - distribute conductive agent - combine the primary material (lithium cobaltate, graphite, etc.), the conductive agent is disseminated during the wetting process, which is an undeniable work phase.The standard procedure takes the most time in this stage, which is also for insurance purposes. After all, SP aggregates are formed by agglomerating particles with a D50 of just 40nm into aggregates of 150-200nm. It will take some time to achieve uniform dispersion without the addition of a dispersant. Because power=torqueangular velocity, the revolution should be performed at a moderate pace for equipment maintenance,the power of the motor is constant.
The main advantage of the dry approach is that it saves time, increases solid content year after year, and reduces solvent loss, which can save hours of sol. Of course, this has equipment and process technology needs. Dry powder mixing—wetting—dispersion—stabilization is a typical dry process flow. Obviously, the difficulty of dry powder mixing is significantly lower than that of wet mixing, yet wetting is critical and tough to master.Wetting is important because if agglomerates are left behind, it is more difficult for the test coat to break up using dispersive shear. Because the linear speed of the standard planetary mixer is only 20m/s, which is far from the recommended 23m/s, and the larger the tank, the more difficult it is to adjust the speed.
It is a mixing process whose primary goal is to produce a homogenous mixture. For example, to make a homogeneous plastic or paste, add a tiny amount of liquid to a powder material, or a small amount of powder to a high-viscosity substance. Kneading procedures are distinguished by the following characteristics:Kneading is frequently accompanied by a heating or cooling procedure. On the one hand, the kneader's unit volume must have an adequate heat transfer surface. To prevent the material from clinging to the wall, the moving components should be able to scrape off the material stuck to the heat transfer surface and send it back to the high shear area.The high shear zone with a short gap may create high shear stress to distribute the material in the dynamic characteristic analysis of the differential mixing kneader and the three-dimensional flow field simulation in the kneader. In the meanwhile, The form of the mixer's driving elements (such as the impeller) may guarantee that the material in the kneader's movement path and range of movement continue to pass through the high-shear zone with tiny gaps, allowing it to be repeatedly sheared and disseminated evenly.The kneading process is complex in comparison to other mixing procedures, the mixing duration is considerable, and only a statistically full mixing state may be reached at the end.