Research On Technology And Performance Characterization Of Silica Preparation From Hami Wollastonite

Silica is also named as precipitate SiO₂, reactive SiO₂ or sediment SiO₂. It is highly dispersed amorphous powder or flocculent powder, lightly mass, high electrical insulation, porosity, hygroscopicity, big specific surface area, and it has the characteristics of great reinforcement; enhancement of viscosity, and good dispersion, suspension and liquefaction features, it has been widely used in the fields of plastics, rubber, paper making, paints, dyes ,inks and other dozens of areas, particularly in the rubber industry, silica is predominant for it's excellent reinforcing and transparency. With the great development of national economy, the demand for silica has been increasing dramatically. Silica is currently regarded as one of the most promising materials.In this paper, silica is prepared through precipitation method with wollastonite which has been proved to be abundant in Hami and Baicheng Xinjiang. The project mainly discusses the technical method to make silica. Three different Preparation Process including direct production, wollastonite's depuration and classified production have been taken into preparing three kinds of silica with wollastonite, and the products have been analyzed using the standard of HG/T 3061—1999, which included following items: the measure of SiO₂ content, heating loss, scorch loss, DBP, pH, specific areas. The influences of the concentration of reaction solution, reaction temperature, pH, and the amount of PEG on the silica DBP have been respectively studied. The factors of influencing silica's performance have been evaluated, and the scheme has been optimized, it has been accomplished to Characterize silica's surface physical and chemical characters such as structure, particle size under the optimized scheme.The contents of all three kinds of SiO₂ are more than 90%, direct production has a SiO₂ content of 93.08%, wollastonite's depuration production has 95.29% and classified production is 98.40%. The specific areas of three productions have been measured by BET. The specific area of direct production is 63.83 m²/g (F level), wollastonite's depuration production is 90.79 m²/g (E level), classified production is 301.84 m²/g (A level). The result of characterizing by SEM, TEM, XRD: the SEM micrograph shows that there are some alveolar micro pores on surface of SiO₂ particles, the TEM micrograph showed that the shape of silica particles was nearly spherical. The structure of silica by classified production was amorphous by XRD analysis. However, the silica prepared by direct production or depuration production contain some crystal structures. The application of silica in rubber, PP, PLA also has been studied primarily.