How can one produce Ferrosilicon

[WFiege]

Hi,
I am a layman, but I wish to know how to make Ferrosilicon.
I realize that one combines silica sand and iron, but I would assume it is more complicated then melting the desire combination and stirring them together.

Wikipedia says,"Ferrosilicon is produced by reduction of silica or sand with coke in presence of scrap iron, millscale, or other source of iron,"

Please offer the details of producing marketable Ferrosilicon.
Thanks,
Bill

 

[0xDEADBEEF]

The details are what is difficult. But the basic process looks simple. It seems that one takes a big furnace, puts in sand, coke and iron and then runs a lot of electrical current through it to make an electrical arc and heat the stuff to 2000°C.

 

[Matcon]

Production of silicon in an arc furnace goes in two stages via silicon carbide:
SiO2+3C=SiC+2CO(g)

SiO2+C=SiO(g)+CO(g)
SiC+SiO(g)=2Si + CO(g)

You can estimate the relative quantities of silica and coke from the above. If you are using impure silica, you will get some of your iron from your feedstock. Expect to lose some silicon as gaseous silicon monoxide, that reacts with air to produce a silica plume from your furnace.

The main function of iron is to decrease the melting point and increase the density.

Pure silicon melts at 1410°C and has a theoretical relative density of 2.33. In practice silicon metal is porous.

Ferrosilicon melts at about 1280°C (liquidus) and has a relative density of about 3.7.

Pure silicon is more likely to float on top of the alloy you wish to inoculate and catch fire than ferro silicon.