Silica fume is a recycling product of industrial soot, mainly the soot produced by ferrosilicon smelting after filtration, the filtered down silica and other oxides cooling cohesion is silica fume, because its main composition is silica, and the particle size is extremely fine, so it is also called microsilica , in addition to a large number of use in cement concrete, there are a variety of research using silica fume to prepare high-performance materials.

Silica fume preparation of White Carbon Black

The current research on the preparation of white carbon black using silica fume mainly focuses on the preparation process, product purity and performance control, however, the produced product is precipitated silica, which has a large performance gap with the silica produced by the fumed method, and the specific research results are as follows:

1. Using low-grade silica fume as the silicon source, nano-SiO2 with a grade of more than 97% was prepared by the process of “acid leaching and purification, HF acid dissolution, hydrolysis and drying”, and its BET specific surface area and average particle size were 210m²/g and 90nm, respectively.
2. Silica fume was added to quicklime and calcined, and then acid leached to produce silica with 99.9% purity, 11.15μm average particle size and 96 whiteness.
3. Acidic silica sol with good stability was prepared from silica fume and calcium oxide by mixing acid with HF to remove iron, high temperature calcination and water solubility.
4. Spherical nano-SiO2 with 98.3% purity was prepared from silica fume with 93.05% grade as raw material by 600°C scorching and decarbonization, preliminary decontamination by hydrochloric acid pickling, decontamination by HF dissolution of glassy shell, decontamination by two-step acid leaching with HC1 and H2SO4, and drying.
5. Using silica fume as the main raw material, the new adsorbent material was prepared by acid washing to increase the specific surface area of silica fume, combined with binder and pore builder, etc. The study showed that it has good adsorption performance.

Preparation of silicon metal from silica fume

The study on the preparation of silicon metal from silica fume is mainly based on the use of silica fume with a grade of 97.5% as the silicon source, and the preparation of silicon metal by acid leaching, low-temperature calcination, magnesium thermal 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 are better than metallurgical silicon and are high-quality raw materials for the preparation of solar grade silicon. Therefore, the preparation of silicon metal using silica fume is an important direction for its high value utilization.

The preparation of silica fume high-performance adsorbent

Silica ash has a large specific surface area and well-developed pores, and has a strong adsorption effect, so the use of silica ash prepared adsorbent materials in wastewater, waste gas, waste liquids and other treatment will have a wide range of applications, currently known research in this area are as follows:

1. The purified silica ash synthesized MCM-41 mesoporous molecular sieve, its pore size is 2 ~ 5nm, has a good effect on the adsorption of heavy metal removal.
2. Silica ash and lithium carbonate as raw materials, through high temperature calcination prepared lithium silicate adsorption materials, good adsorption of CO2.
3. The silica ash dissolved to prepare water glass, through the sol-gel method of synthesis of hydrophobic silica, can be used for adsorption of oil and gas recovery.

The application in the gel material

As silica ash can be prepared by high temperature calcination or alkali dissolution of water glass, therefore, whether silica ash or water glass as a silicon source for the preparation of silica aerogel, can achieve high value-added utilization of silica ash. The silica aerogel prepared by using silica ash as silicon source has high porosity, high strength, low density, good heat insulation, and non-toxic characteristics, and is expected to be widely used in aerospace, construction, medicine and other industries.

1. Silica fume is mixed with calcium oxide and calcined, and then acid-sol-gel method is used to produce silica aerogel with narrow particle size distribution and high purity.
2. Silica aerogel is prepared by acid addition-sol gel method with water glass as silicon source.
3. Silica aerogel was prepared by carbonization-drying by mixing asbestos fleece fiber in water glass, which has good strength and thermal insulation performance.

These studies on the application of silica fume in the preparation of high-performance materials show that the resourceful, comprehensive and high-value utilization of silica fume and the deep processing of silica fume to improve its physical and chemical properties are the main research directions, and the quality of silica fume used in these studies are all different, which has positive significance for the utilization of silica fume of different specifications.

HSA Microsilica

HSA has been a global supplier of high-quality silica fume since 2001. We have established long-term and stable cooperation with many concrete construction companies around the world to provide our customers with high-quality silica fume with different contents and different uses, fully satisfying all kinds of concrete project needs.

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