Oxidation Behavior of Silicon, Phosphorus and Vanadium in Carbon-saturated Iron Melt by Sodium Carbonate

Abstract

From an experiment that Na₂CO₃ reacted with solid Fe-54% V alloy at 1100°C, the following equation was derived for the reaction of vanadium oxidation by soda ash.
Na₂CO₃+ 4/5V= Na₂O+ 2/5V₂O₅+ C
Vanadium valencies in the soda flux (Na₂CO₃, Na₂CO₃-FeO) reacting with carbon-saturated iron melt have been examined as a function of time. The V₂O₅ produced by the above equation was found to gradually reduced by carbon and/or silicon, changing to the valency V⁵⁺→V⁴⁺→V³⁺. The reduction rate of vanadium oxide was reduced by the addition of iron oxide.
The oxidation behavior of phosphorus, vanadium, and silicon in carbon-saturated iron melt has been studied by use of soda flux (Na₂CO₃, Na₂CO₃-Fe₂O₃) at 1300°C. The oxidation of phosphorus and vanadium were initially retarded if a small amount of flux was added by installments and after the end of flux addition the reversion of phosphorus and vanadium occurred. In comparison with the results obtained in the addition of soda flux by a lump, the retardation of initial oxidation was explained by the fact that the reversion rate of phosphorus and vanadium was considerably fast. The effect of Fe₂O₃ addition to the flux was found to be significant in both experiments using a lump and installment additions. The extensive removal of vanadium was observed in the addition of Fe₂O₃ by installments, while neither dephosphorization reaction nor the vanadium reversion took place. The same oxidation behavior found in the Na₂CO₃-Fe₂O₃ flux was obtained in an experiment using the CaO-CaF₂-Fe₂O₃ flux.