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Application of Micro Silica Fume in High Performance Materials

Micro silica fume for making silicon metal

Micro Silica Fume can not only be applied to concrete, cement and other crude industries, but now the scientific and technological research has begun to purify and modify Micro Silica Fume to prepare a high purity and fineness powder, so that it can be applied to the research and development of some high-end products, which opens up the market value of Micro Silica Fume and gives it a higher value utilization space. So, how can Micro Silica Fume be utilized with high value? Henan Superior Abrasives today provides a detailed summary of the uses and applications.

Micro silica fume for making nano silica

Purification of Micro Silica Fume by acid leaching

The Micro Silica Fume is treated by the natural sedimentation method of hydrochloric acid and then washed with 1:200 dilute hydrofluoric acid for 5 min in order to release the wrapping phenomenon of glassy silica, and then carried out a two-step cycle of hydrochloric acid and sulfuric acid pickling process, so that the purity of silica in the Micro Silica Fume can reach 98.3%.

Only hydrofluoric acid can dissolve the glassy silica on the surface of the powder, but this process also leads to the loss of silica, which also cannot improve the content of silica well, so the Micro Silica Fume can be mixed with calcium oxide, which is calcined at high temperature to generate calcium silicate, and then dissolved by acid leaching to obtain a silica product with a purity of 99.9%. This process both shortens the reaction process and also removes the protective effect of the glassy state on the surface of the microsilica powder. The added calcium oxide destroys the ternary structure of silicon, iron and other metals in the powder, so that the iron and other metal impurities are easily removed by dissolving in hydrochloric acid, which improves the removal rate of the acid leaching process.

Hot alkali dissolution of silica in microsilica powder

Only using the acid leaching process to remove the metal impurities in the powder to achieve the purpose of silica purification, because some of the impurities are wrapped by the glassy silica, it is difficult to contact and react with the acid, so it can not meet the purity requirements of silica. For this purpose, silica can be extracted from the microsilica powder and then gel to form a high purity silica product.

Therefore, the researchers invented a process to prepare high purity, fine particle size silica products by carbonizing the water glass solution prepared by dissolving microsilica powder with sodium hydroxide as the silica source and carbonizing it by carbon dioxide exhaust gas. This process not only makes full use of the waste and reduces the pollution of the environment by greenhouse gases, but also brings some revenue to the enterprises and promotes the smooth implementation of environmental pollution remediation.

Hydrofluoric acid dissolves silica in microsilica powder

Through hydrochloric acid acid leaching to remove metal impurities after the precipitation injected into the hydrofluoric acid solution to dissolve it, to produce H: SiF sol, and then the resulting solution will be added to the ammonia solution doped with PEG6000 at 60 ℃ for neutralization and hydrolysis, the preparation of high-purity hydrated silica precipitate and then dried and burned to produce nano-silica powder. This process is similar to the process of alkali dissolution followed by acid purification of silica, the main advantage of which is that hydrofluoric acid can dissolve the silica in the glassy state on the surface of the microsilica powder, while alkali cannot do so.

Micro silica fume for making silicon metal

The research on the preparation of silicon metal from microsilica powder is mainly based on the preparation of silicon metal from microsilica powder with a grade of 97.5% as the silicon source through the steps of acid leaching, low temperature calcination, magnesium heat reduction, and acid leaching after reduction. The prepared silicon metal contains more than 99% silicon and less than 3g/t and 12g/t of B and P, respectively, which is better than metallurgical silicon and is a high-quality raw material for the preparation of solar grade silicon. Therefore, the use of microsilica powder for the preparation of silicon metal is an important direction for its high value utilization.

Micro silica fume for making high performance adsorbent

The use of Micro Silica Fume characteristics of large specific surface area, can play a good role in its adsorption. The MCM-41 mesoporous molecular sieve with a pore size range of 2- 5 nm can be synthesized from the acid-impregnated purified microsilica powder and used as an adsorbent to complete the adsorption of heavy metal ions. The high purity microsilica powder (95% ~ 98%,wt) after acid leaching was used for sailing and so on. The mesoporous silica molecular sieves synthesized by adding sodium hydroxide solution and structure directing agent, the dirty heavy metal adsorption process achieved good results and greatly improved the added value of the microsilica powder.

Hydrophobic silica, synthesized by sol-gel method with water glass as the silica source, plays an important role in oil and gas recovery, and its adsorption and desorption properties are superior compared with those of common adsorbents. Lithium silicate adsorbent material made from lithium carbonate and microsilica powder and calcined by high temperature solid phase method in the ratio of 1.94 molar ratio has played a good role in the treatment of carbon dioxide gas in the atmosphere.

Application of Micro Silica Fume in composite materials

With the increase in the production of microsilica powder, people have gradually expanded the scope of application of microsilica powder, such as the modification of asphalt with SBS by adding microsilica powder to form a microsilica powder/SBS composite material, which is used to improve the stability of asphalt under high temperature conditions and increase its hardness. Nickel/silicon and iron/silicon alloy composites were successfully synthesized by electroplating and sol-gel technology, which prevented the corrosion of metals in acid and made the material insulating.

Application of Micro Silica Fume in gel materials

The use of inorganic materials as a silicon source for the preparation of highly utilizable silicon aerogels has attracted the attention of various research institutions. In response, there is a Micro Silica Fume, diatomaceous earth and other high silica content, low price of the powder as a silicon source, by adding calcium oxide calcination after adding acid through the sol-gel method to produce a silica aerogel products with few impurities, high purity and narrow particle size distribution. However, this method requires calcination of inorganic powder under high temperature conditions, which consumes more energy. If the powder is added to sodium hydroxide solution to make water glass solution as silicon source to prepare aerogel will reduce the cost of production. So later on, a kind of white silica aerogel product was invented by adding acid to neutralize the sol-gel solution with water glass as the silica source and using sol-gel method. And now the silica aerogel material prepared by carbonization and atmospheric pressure drying has good strength and heat insulation performance by using water glass as the silica source and mixing with asbestos fleece fiber as the reinforcing material of silica aerogel.

High Performance Silica Fume Manufacturer

Micro silica fume is not only used in construction and engineering, but also widely used in high performance materials, and the future development prospect of micro silica fume is very broad. Henan Superior Abrasives produces and develops high quality white, gray and raw gray microsilica powder, etc. The microsilica powder produced by Henan Superior Abrasives has fine particles, large specific surface area and a wide range of use, welcome interested parties to leave a message or email us.

Email: sales@superior-abrasives.com

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