Silica Fume

is also called condensed silica fume

Keywords

silica fume, microsilica, silica fume, microsilica, condensed SiO2 (silica) fume, amorphous silica, silicon dioxide powder, silica powder

Overview

When ferroalloy is smelting ferrosilicon and industrial silicon (metal silicon), a large amount of highly volatile SiO2 and Si gas is produced in the mine thermoelectric furnace, which is quickly oxidized and precipitated with air after the gas is discharged. It is a by-product of large-scale industrial smelting. The entire process needs to be recycled with dust removal and environmental protection equipment. Because of its low density, encryption equipment is also needed for encryption.

Nature and principle

Silicon powder is added to special refractory materials (such as Portland cement, kiln bricks, etc.) to form a multi-layer protective layer during oxidation. It has good mechanical properties and high temperature and oxidation resistance. After adding ultra-fine silicon powder to special refractory materials , Its fluidity, sintering, bonding, and pore filling performance have been improved to varying degrees. Improve the density and strength of the structure, reduce the wear rate of the material, and enhance the corrosion resistance.

Physical properties

1. Appearance: gray or off-white powder

2. Refractoriness>1600℃

3. Bulk density: 1600~1700 kg/m3.

Chemical composition

5. Fineness: 80% of the silica fume has a fineness of less than 1um, the average particle size is 0.1-0.3um, and the specific surface area is 20-28m2/g. Its fineness and specific surface area are about 80-100 times that of cement and 50-70 times that of fly ash.

6. Particle morphology and mineral phase structure: During the formation process of silica fume, due to the effect of surface tension during the phase transition, amorphous spherical particles of amorphous phase are formed, and the surface is relatively smooth, and some have multiple circles. An agglomerate of spherical particles sticking together. It is a kind of volcanic ash material with large specific surface area and high activity. For materials mixed with silica fume, tiny spheres can play a lubricating effect.

Features

Cement or concrete admixture

Microsilica fume can fill the pores between cement particles, and at the same time form a gel with the hydration product, and react with the alkaline material magnesium oxide to form a gel. In cement-based concrete, mortar, and refractory castables, mixing a proper amount of silica fume can play the following roles:

1. Significantly improve the compressive, flexural, impermeable, anti-corrosion, impact and wear resistance properties.

2. It has the functions of retaining water, preventing segregation and bleeding, and greatly reducing the resistance of concrete pumping.

3. Significantly prolong the service life of concrete. .

4. Significantly reduce the floor ash of sprayed concrete and castables, and increase the thickness of a single sprayed layer.

5. It is a necessary ingredient of high-strength concrete

6. Microsilica fume is amorphous spherical particles, which can improve the rheological properties of concrete.

7. Improve the strength and durability of concrete.

Scope of application

Commercial concrete, high-strength concrete, self-leveling concrete, unshaped refractory, dry-mixed (pre-mixed) mortar, high-strength non-shrink grouting, wear-resistant industrial floor, repair mortar, polymer mortar, thermal insulation mortar, impermeable concrete , Concrete compacting agent, concrete preservative, cement-based polymer waterproofing agent; reinforcement of rubber, plastic, unsaturated polyester, paint, coating and other polymer materials, modification of ceramic products, etc.