Method of manufacturing silicon dioxide
I. INTRODUCTION
Silicon dioxide is an important inorganic chemical widely used in many fields such as ceramics, glass, rubber, plastics, coatings, food additives and so on. Due to its unique physical and chemical properties, silicon dioxide has an important position in the field of raw materials for chemical production. In this paper, we will introduce the manufacturing methods of silicon dioxide, including precipitation method, sol-gel method, fumed method and so on.
II. Precipitation method
The precipitation method is one of the common methods for the preparation of silicon dioxide. This method obtains silica by reacting a silicate solution with an acid or alkaline absorbent to precipitate the silicate ions in the silicate. The steps are as follows:
1. mixing the silicate solution with an acid or alkaline absorbent to react the silicate ions in the silicate to form a silicate precipitate.
2. The silicate precipitate is washed, filtered and dried to obtain a silica product.
The advantage of the precipitation method is that the process is simple and inexpensive, but the resulting product has lower purity and larger particles, requiring further processing.
Third, sol-gel method
Sol-gel method is a method for the preparation of high purity, ultrafine silica. The method obtains silica by hydrolyzing and condensing the silicate solution to form a sol, and then going through the steps of gelation, drying, and calcination. The specific steps are as follows:
1. Silicate solution is added to water and hydrolyzed to form silicate sol.
2. Add acid or alkaline catalyst to promote the condensation reaction of the sol to form a gel.
3. The gel is dried and calcined to obtain a silica product.
The advantage of the sol-gel method is that the resulting product has high purity and fine particles, but the process is more complex and costly.
Four, fumed method
Fumed method is a method of preparing high purity, special form of silica. This method generates silicon dioxide by making silicon tetrachloride and other silicon-containing gases oxidize and react at high temperatures. The specific steps are as follows:
1. Silicon tetrachloride and other silica-containing gases are introduced into a high-temperature combustion chamber.
2. Admitting an oxidizing agent, such as oxygen or air, to oxidize the silicon-containing gas at a high temperature to generate silicon dioxide.
3. Silicon dioxide products are obtained through steps such as cooling and collection.
The advantages of the fuming method are high purity of the resulting product and controllable particle morphology, but the equipment investment is larger and the production cost is higher.
V. Conclusion
There are various methods for the manufacture of silica, including precipitation method, sol-gel method, fumed method and so on. The purity, particle size and morphology of the products obtained from different methods are different, and the suitable manufacturing method should be selected according to the specific application areas. In the future, with the continuous progress of science and technology and environmental protection requirements, the manufacturing method of silica will continue to be optimized and improved.
