Precipitated silicas are produced by chemical reactions and precipitation, which is achieved by neutralizing a solution of sodium silicate with an acid, often sulfuric acid.The by-product, sodium sulfate, is eliminated via filtration. The remaining silica is then dried and formed based on its final application. The precipitation stage determined the microscopic particle morphology for most of the silica's application properties.
Key precipitated silica manufacturing process stages include precipitation, filtration, drying and milling.
During the precipitation stage, product properties may be varied through changes in composition and ratio of reactants, reaction time, temperature and concentration. The important characteristics that result from the precipitation process include physical properties such as structure (oil absorption and compressibility), and chemical properties such as pH, silanol group density and optical properties.
During filtration, drying and milling, salts formed during the precipitation stage are washed out, and depending on the product, the solids content of the filter cake can range from 15-30 percent. As a result, drying is a major cost component in manufacturing precipitated silica.
Finally, the dried Silica can be milled in a variety of ways to reduce the size of the agglomerates formed during the drying process. Rhodia precipitated silicas are staged in large silos before being bulk loaded or packaged for shipment to customers.
Key precipitated silica manufacturing process stages include precipitation, filtration, drying and milling.
During the precipitation stage, product properties may be varied through changes in composition and ratio of reactants, reaction time, temperature and concentration. The important characteristics that result from the precipitation process include physical properties such as structure (oil absorption and compressibility), and chemical properties such as pH, silanol group density and optical properties.
During filtration, drying and milling, salts formed during the precipitation stage are washed out, and depending on the product, the solids content of the filter cake can range from 15-30 percent. As a result, drying is a major cost component in manufacturing precipitated silica.
Finally, the dried Silica can be milled in a variety of ways to reduce the size of the agglomerates formed during the drying process. Rhodia precipitated silicas are staged in large silos before being bulk loaded or packaged for shipment to customers.
