A Study On Continuous Preparation Of Silica By High Gravity Sulfuric Acid Precipitation Method And The Drying Way

Silica powder is a kind of very excellent functional inorganic powder materials, so it is widely used in rubber, dope industry, printing ink, plastic, foodstuff, toothpaste and other industries. Now the sulfuric acid precipitation is the primary method to produce silica powder around the world, and the domestic corporations mostly adopt traditional producing technics with a series of disadvantages like high consuming cost, low single producing capacity, rigorous operating condition, long reacting time, big particle size and small reactors which are not suitable to be magnified. The high gravity sulfuric acid precipitation method to prepare silica is a new technology with simple process, short reacting time, easy operation and industrialization.In order to make the high gravity sulfuric acid precipitation method be continuous, in the paper the rotating packed bed’s main parts are reconstructed, the technics is designed, and then the continuous experiment is studied.The mass fraction of sulfuric acid and the concentration of sodium silicat change in this experiment to investigate the effect on the quality of silica powder and the producing capacity. The results indicate as follow:Along with the mass fraction of sulfuric acid increasing, the average particle size of silica is less than10nm, the specific surface area and the producing capacity firstly increase, then decrease, finally increase again, but the DBP absorption value changes by contraries with them. Except the concentration of sodium silicat is10%, other concentrations all make the process appear gelatin. When the mass fraction of sulfuric acid is25%, and the concentration of sodium silicat is10%, the producing capacity is the most.In this paper, the other experimental content is to dry silica gelatin by supercritical ethanol technology, after being prepared in rotating packed bed and disposed. The volume ratio of solution to the reactor tank, the mass of filtrate-cake, and N2prepresurization atmosphere change to investigate the effect on silica powder. The results show that:The more volume ratio of solution to the reactor tank or the bigger mass of filtrate-cake change, the greater the contact angle is. The contact angle changes rulelessly as the N2prepresurization atmosphere varies. Along with the three factors change, the contact angle is almost all above130°, which presents strong hydrophobicity, and the other drying quality are different. When the volume ratio of solution to the reactor tank is0.3, and the mass of filtrate-cake is25g, the whole quality of silica is the best.