ferrosilicon is a ferroalloy
DESCRIPTION
Production and uses of Ferrosilicon is a FerroalloyTRANSCRIPT
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.
Production and reactions
Ferrosilicon is produced by reduction of silica or sand with coke in presence of iron.
Typical sources of iron are scrap iron, millscale. 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. An
overabundance of silica is used to prevent formation of silicon carbide. Microsilica is a
useful byproduct.
Uses
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 (so called blocking the heat); ferromanganese, spiegeleisen, silicides of
calcium, and many other materials are used for the same purpose. It can be used to
make other ferroalloys. Ferrosilicon is also used for manufacture of silicon,
corrosion-resistant and high-temperature resistant ferrous silicon alloys, and silicon
steel for electromotors and transformer cores. In the manufacture of cast iron,
ferrosilicon is used for inoculation of the iron to accelerate graphitization. In arc
welding, ferrosilicon can be found in some electrode coatings.
Ferrosilicon is a basis for manufacture of prealloys like magnesium ferrosilicon
(MgFeSi), used for production of ductile iron. MgFeSi contains 3–42% magnesium and
small amounts of rare earth metals. Ferrosilicon is also important as an additive to cast
irons for controlling the initial content of silicon.
Ferrosilicon is also used in the Pidgeon process to make magnesium from dolomite.
Treatment of high-silicon ferrosilicon with hydrogen chloride is the basis of the
industrial synthesis of trichlorosilane.