Silicothermic reduction

Fig. 4. Process flow sheets for (a) the silicothermic reduction and (b) the MOR process. See text.

Silicothermic reduction is also an important technique for the production of ferroalloys. The production of low-carbon ferrochrome and of ferrovanadium are carried out by this technique. The overall reaction for the reduction of vanadium pentoxide by ferrosilicon to yield ferrovanadium can be represented as... 

Most elements can easily be alloyed to liquid silicon, through silicothermic reduction of oxides or by adding pure metals. In this way a variety of special requirements can be fulfilled. Metallurgical silicon is now supplied in a wide range of qualities. Almost every MCS or TCS process operator has his own specification, whereas the aluminum market is supplied with a range of standard specifications. 

Silicothermal reduction and nitridation (SRN) is an alternative synthesis method for SiAlON ceramics, in which the carbon is replaced by elemental silicon as the reducing agent. This produces SiAlONs without the formation of greenhouse gases, by reactions such as ... 

Ferrochrome (UK, France), or ferrochromium (USA), is a master alloy of iron and chromium containing between 40 and 75 wt.% Cr and varying amounts of carbon and silicon. It is prepared industrially by three different electrothermal processes—the carbothermic, the silicothermic, or the aluminothermic reduction of chromite ore, which is used as the main source of chromium. In the carbothermic process, a charge of chromite ore mixed with lime as fluxing agent is reduced by metallurgical coke or coal as reductant in a three-phase submerged-arc furnace. The overall chemical reaction involved is as follows ... 

---