Silica fume (also called silicon ash or condensed silica fume) is
formed by condensation and sediment of strongly-volatile SiO2 and
Si from ore-smelting electric furnaces which are exhausted and
oxidized with air during smelting of ferrosilicon and industrial
silicon (metallic silicon) with ferroalloy. It is one byproduct of
large-scale industrial smelting, and the whole process requires
dedusting device to recycle it. As its mass is low, sometimes it
needs an encryption device due to different purposes.
|Index of Silica Fume (Take SiO2 92% for example)|
|Loss on ignition||≤6||1-2|
|Water demand ratio||≤125||120|
|Specific surface area||≥15000||18000-20000|
It is widely applied in refractory industry, and plays an important
role in improvement of amorphous refractory.
(1) There are many pores in conventional refractory, and to fill
silica fume in the pores is good for improvement of volume density,
reduction of porosity and sharp enhancement of strength.
(2) Silica fume has stronger activity, can form colloid particles
in water. After adding some dispersing agent, it can enhance
flowability and improve casting property.
(3) Silica fume is easy to form Si-OH base in water, and has
stronger hydrophilicity and activity, so it is able to enhance
refractory condensation, improve high-temperature property and
prolong service life of refractory products.
Silica fume is extensively used in the refractory industry,
specifically showing as following in practice.