Silica Preparation Of High Purity And Ultrafine Silica

The development of 21st century's new techology not only has provided requestment to the chemical composition of materials, but also is the strict with the formation and pattern of them. Research, production and application on high purity, ultra-fine materials' development has become an important part of modern technology. With the development of modern science and technology, ultra-fine and high-purity silica is widely used in in the electronic industry and aerospace technology, and it is also used in in the coating, plastics, lubricants, nanometer biological materials and other industries, which entitles the preparation of ultra-fine and high-purity silica more increasing attention.Based on the theoretical analysis, the effects of leaching temperature, pressure, the particle size of silica and leaching time on leaching rate are researched while silica as the raw materials in leaching process. The effects of acid concentration, pH of titration end-point, stirring speed, ultrasonic, aging time and aging temperature, alcohol, chelators on purity and size distribution are researched. In addition, the effect of different acids on purity, particle size distribution and morphology is researched in the preparation process. Furthermore, the single factor experiments were studied according to possible influencing factors of purity and size distribution in chemical precipitation process. At last, the optimum process conditions of preparation of ultra-fine and high-purity silica were obtained.In addition, the process mechanism of the experiment was also discussed. ICP-AES, Variancary5000, SEM, TG-DTA, RISE-2002 were employed to characterize the performance of products. The results show that the ultra-fine and high-purity silica with the average particle size of 400 nm was obtained when acetic acid is used as the precipitate, and the total content of impurities is 0.0334%. While the product with the average particle size of 28.35μm was obtained when sulfuric acid is used as the precipitate, and the total content of impurities is 0.0396%. While the product with the average particle size of 28.68μm was obtained when hydrochloric acid is used as the precipitate, and the total content of impurities is 0.0462%.