In the production process of the micro-silica fume ferroalloy smelting furnace, the gaseous substances generated by the reduction of SiO2 in the silica are oxidized to form SiO2 particles after escaping from the material surface. It is an off-white ultrafine powder, which is smooth and spherical under the scanning electron microscope, and the average particle size is less than 1mm. The specific surface area measured by nitrogen adsorption method is 25~30m2/g, which is 50~100 times larger than that of cement (0.4 m2/g). The bulk density is 200~250kg/m3, the specific gravity is 2.1~3.0 kg/m3, the pH is 6.7~8, and the pozzolan activity is 90%.
Due to its excellent physical and chemical properties, micro-silica powder is an important nano-micron inorganic non-metallic material. It is called “magic material” abroad. It has been widely used in construction, rubber, ceramics and refractory materials. And the scope of use is expanding.

It is reported that while importing ferroalloy products from my country, Japan also imports a large number of micro-silica powders. After purification and processing, high-performance ceramic materials are produced for use in high-tech fields such as aviation and aerospace. However, my country has not yet mastered key technologies in purification, encryption and high-performance ceramic materials. On the other hand, if these dusts are not treated, they will become inhalable particles after entering the atmosphere, which can directly enter the human lungs and cause great harm. Therefore, the recycling of microsilica is not only reflected in its economic benefits, but also in environmental benefits.

Since 1990, my country’s metallurgical furnace microsilica products have been sold well in 18 countries and regions such as the United States, Japan, Britain, Germany, Hong Kong and Taiwan, and the annual foreign exchange earnings have reached more than 10 million US dollars, and are well received by domestic and foreign users. However, at present, only the original micro-silica fume collected by the bag filter is sold. Due to the insufficient technical development in dust removal, purification, encryption and comprehensive utilization of micro-silica fume, it has affected the economy of micro-silica fume recycling to a certain extent. efficiency, and product sales are constrained by external market conditions. Due to the light bulk density of micro-silica fume and the density of only 200kg/m3, the cost of transportation and packaging is relatively high.

In addition, high-purity micro-silica fume is widely used in refractory materials, chemical industry and other fields. Now many countries have put forward requirements for the supply of this product. However, at present, the purity of micro-silica fume in my country is not enough, and the SiO2 content can only reach about 92%. While improving the dust collection rate, the content of SiO2 can be increased to more than 96%, and the impurities such as Fe2O3 and C can be removed, so the sales price per ton can be greatly increased, bringing more significant economic benefits to the enterprise.