Silica fume is a by-product of smelting of silicon metal or ferrosilicon. It is made of highly volatile SiO2 and Si gas, which is oxidized and condensed and precipitated with air. High-strength concrete, Microsilica powder shotcrete, silica fume mortar, and low cement use silica fume as an additive to increase its strength, also know as microsilica . In recent years, with the increasing demand for high-strength concrete in the market, many ferroalloy production enterprises are equipped with dust collection equipment, producing and selling Microsilica powder, and developing and introducing encryption technology.The Microsilica powder is collected from the electric furnace chimney, and the electric furnace outlet flue gas passes through the hood and the main flue gas duct, and is cooled by a cooling device to enter. The cyclone separates the dust collector and passes through the bag filter. The microsilica powder thus obtained is called "Original Silica Fume", and its initial density is only 150-200kg/m3, which is very expensive to transport. Therefore, the encrypted Microsilica powder is spherical, and the bulk specific gravity is bulk. The Microsilica powder is increased from 0.2t/m3 to 0.3~0.6t/m3, which can reduce the packaging and transportation costs by about 30~60%. In short, transportation costs are one of the biggest differences between densified and undensified silica fume. Densified silica fume can reduce costs, reduce dust during loading and unloading, and improve the working environment of workers. At the same time, it is convenient for mechanical pumping, which is good for stirring.Densified and undensified silica fume have no change in chemical cost, only differing in density. The resulting change in fluidity is negligible for general high-density concrete. According to the density, it can be divided into undensified silica fume, half-densified silica fume and full-densified silica fume.