Kinetics of Nitrogen Disorption from Low Nitrogen Liquid Iron by Blowing Ar and Reducing Gas Mixture or by Top Injection of Iron Ore Powder under Reduced Pressure

Abstract

The effects of blowing Ar and reducing gas mixture or top injection of iron ore powder on the rate of nitrogen removal from liquid iron under reduced pressure have been studied using a vacuum induction furnace containing 12 kg metal at 1 600°C.
1) In the case of blowing Ar and reducing gas mixture, the value of chemical reaction rate constant, k_r, was slightly greater than that in the case of only Ar blowing. Even in the former case, k_r depended strongly on sulfur content in metal in the range of low oxygen content.
2) In the case of blowing Ar and hydrocarbon gas mixture, especialy, oxygen content in metal decreased and the rate of nitrogen removal increased remarkably.
3) In the case of top injection of iron ore powder, the rate of nitrogen removal was lower than that without the powder, when the decarburization rate, V_c, was lower than the critical decarburization rate, V_C^a. However, the rate of nitrogen removal increased with the increase of when V_C was greater than V_C^a. V_C^a increased with the decrease of sulfur content.
4) The reason of why the rate of nitrogen removal increased by top injection iron ore powder was attributable to the increase of gas/metal interfacial area by CO gas evolution.