If all you want is a source of silicon for reduction, there's no need to use elemental silicon. If crude silicon works for you, then ferrosilicon should as well.
There are four low-melting eutectic points, that is local minima on the phase diagram. The one with the greatest percentage of silicon is the eutectic
of FeSi and Si, at around 60% Si. But the whole range from ~ 50% Si to 60% Si has a melting point at 1207 - 1220 °C, a couple hundred degrees
lower than that of Si itself at 1414 °C. This is rather easier to get to, as the T4 ratio is 1.8 (that's ratio of radiative heat
loss).
And it's a lot easier to make an arc furnace than screwing around with microwaves. Welding rods, castable refractory, and an ammeter (to know when to
push the rods in) is all you really need. At the materials are dirt cheap: sand, carbon, and steel scrap. |