OXIDATION BEHAVIOR OF SILICON, PHOSPHORUS AND NIOBIUM IN CARBON-SATURATED IRON MELT WITH SODIUM CARBONATE.

Iron ore containing a low Nb//2O//5 content has been proposed as a usable resource of niobium extracted from hot metal by selective oxidation. This behavior has been studied at 1300 degree C with soda (Na//2CO//3, Na//2CO//3-Fe//2O//3) and lime fluxes (CaO-CaF//2-Fe//2O//3). Phosphorus and niobium were oxidized in initial retardation when the fluxes were added by installments. Reversion occurred along with desiliconization after completion of the addition. In comparison with addition of the soda flux by a lump, retardation is explained by fast reversion rates. Extensive removals of silicon and niobium were observed in the addition of Fe//2O//3 by installments, and no dephosphorization took place. When Na//2CO//3 was added to a melt containing silicon, phosphorus, manganese and niobium, removal of niobium was possible without the oxidation of manganese if silicon was oxidized to a low value.