What are the factors that determine the activity of silicon metal powder?
The activity of silicon metal powders obtained by different ball milling methods is different, and the factors that determine the activity are as follows: microstructure, specific surface area, particle size distribution, surface protection and the amount of steel used in equipment.
(1) Microstructure: the silicon whose chemical composition meets the required indicators has a better microstructure in the refining process, which ensures that it has a better activity to participate in the reaction, that is, its natural or natural nature. The degradation of the natural microstructure should be minimized during grinding, and the deformation between the grains and grain groups should be reduced, so that most of the silicon metal powder (more than 99.8%) still retains its original natural microstructure. Of the four methods listed, punching and spinning is the better method. Because the silicon is broken in the air, it is broken along the weaker links of the body, without the structural deformation caused by extrusion, grinding, etc.
(2) Specific surface area: the surface area of the powder is the surface area of the unit mass, m2/g, is an important indicator of the ability to participate in chemical reaction. The specific surface area of metal silicon powder is larger, the reaction speed is faster, the reaction is more complete, the silicon utilization rate is higher, the reaction zone flow pattern is better, the silicon consumption rate is lower, which shows its high activity. Therefore, surface area has become an important index of silica powder activity. The powders have a better specific surface area.
(3) Particle size classification: the direct synthesis method is gradually completed in the fluidized state, the material particle size gradually changes, the surface is constantly updated, the reaction is all, the specific consumption of silicon is also significantly reduced. Therefore, the particle size of silicon metal powder should be matched to the particle size level to obtain better results and formulate the corresponding better particle size distribution. Therefore, the grinding method must ensure that the particle size composition is adjustable and the yield is high. For example, when the particle size of 1T silicon powder is about 85% or above, it is a more appropriate synthesis reaction. This is the raw material index of silicon metal powder used in the fluidized bed of 100,000 t/a organosilicon coarse monomer. (4) surface protection: the production of qualified finished silicon powder in line with the requirements of quality and particle index, the surface needs active protection.
