There are many factors that affect the grinding fineness of vertical sand mills, mainly external and internal reasons.
The external cause is due to the addition of dispersant, the particle size of the raw materials and other reasons. Here we mainly discuss the influence of dispersant on the fineness of grinding.
When the vertical sand mill is running, the crushing of the material particles firstly depends on the collision, squeezing, shearing and other effects between the high-speed moving abrasive particles, so that the size of the material particles is reduced and the specific surface is increased.
With the continuous refinement of the particle size, the particles will re-aggregate under the action of van der Waals force, electric double layer and other static electricity. Therefore, it can be considered that after the particles are ultra-finely pulverized to a certain extent, a reversible process of "pulverization-aggregation" will occur with a series of qualitative changes in physical and chemical properties. If the speeds of the positive and negative processes are equal, that is, the dynamic equilibrium of the crushing process is reached, the particle size reaches the limit value. At this time, it is futile to further extend the crushing time. Since the mechanical force at this time is not enough to further decompose the polymer, it can only be used to maintain the balance of pulverization, and it is possible to produce more small particle aggregates. Therefore, the so-called "reverse grinding" and "returning coarse" phenomenon Will appear. To a certain extent, choosing a suitable dispersant is the only effective way to solve the phenomenon of "reverse grinding" and "returning coarse". The dispersant has an influence on the van der Waals force between particles, and the space repulsion of the solvation film and the adsorption layer.
Therefore, the selection of ultrafine grinding dispersant is a complicated and difficult task. All factors should be considered comprehensively. Only under the premise of ensuring that the dispersant does not affect the product performance and system, the appropriate dispersant and its amount should be selected. , Reduce the soft agglomerates between particles in the ultrafine grinding slurry, make the particles dispersed and stable in the system, so as to achieve the grinding fineness of the sand vertical sand mill.
Internal factors, internal factors, own structure and process design.
In recent years, sand mills have been rapidly developed as a high-efficiency and energy-saving ultrafine crushing equipment.
www.mixerbeadmill.com
