silicothermic process[¦sil·ə·kō′thər·mik ′prä·səs]
the production of metals and alloys by the reduction of ores or concentrates of metal oxides with silicon. The basis of the process is that the affinity of silicon for oxygen (a change in the isobaric potential of oxide formation) is higher than that of reduced metal. Silicothermic processes are carried out in arc furnaces, since the heat released upon reduction is not sufficient for melting or for the required heating of smelted products; the necessary heat is supplied by electric heating. The silicon used in these processes is usually in high-silicon alloy form, such as ferrosilicon, silicomanganese, and ferrochrome silicon, in which the carbon content decreases as the silicon content increases.
The silicothermic process is used in obtaining ferroalloys and hardeners with a low carbon content for use in the smelting of high-grade steels. Silicon interacts with many metals to form strong chemical compounds called suicides, which makes the reduction reaction more complete. This makes it possible to use the silicothermic method to reduce the oxides of calcium, magnesium, zirconium, and rare-earth elements—a process otherwise difficult to achieve. The alloys obtained always have a high silicon content.
V. A. BOGOLIUBOV