Ferrosilicon is a ferroalloy, an alloy of iron and silicon with an average silicon content between 15 and 90 weight percent. It contains a high proportion of iron silicides. Ferrosilicon is produced by reduction of silica or sand with coke in presence of scrap iron, millscale, or other source of iron.
Ferrosilicons with silicon content up to about 15% are made in blast furnaces lined with acid fire bricks. Ferrosilicons with higher silicon content are made in electric arc furnaces. The usual formulations on the market are ferrosilicons with 15%, 45%, 75%, and 90% silicon. The remainder is iron, with about 2% consisting of other elements like aluminium and calcium.
Chemical Composition :
|1. Silicon||:||70.67 %|
|2. Phosphorous||:||0.041 %|
|3. Sulphur||:||0.020 %|
|4. Carbon||:||0.098 %|
|5. Aluminium||:||1.110 %|
|6. Manganese||:||0.000 %|
|7. Ferrous / Iron||:||28.06 %|
Ferrosilicon is used as a source of silicon to reduce metals from their oxides and to deoxidize steel and other ferrous alloys. This prevents the loss of carbon from the molten steel.
It can be used to make other ferroalloys.
In the manufacture of cast iron, ferrosilicon is used for inoculation of the iron to accelerate graphitization. Ferrosilicon is also important as an additive to cast irons for controlling the initial content of silicon.
In arc welding, ferrosilicon can be found in some electrode coatings.
Ferrosilicon is also used in the Pidgeon process to make magnesium from dolomite.