The rate of nitrogen desorption from liquid iron by blowing argon gas under the condition of non-inductive stirring

The nitrogen desorption reaction by blowing argon gas onto the surface of l iquid iron containing various oxygen contents has been studied in a resista nce furnace. Using a periscopic high temperature lens the Marangoni convect ion was qualitatively observed in the process of nitrogen desorption. In te rms of the experimental results and gas-liquid metal reaction kinetic theor y, the procedure of the nitrogen desorption is discussed. The nitrogen deso rption from liquid iron under the condition of non-inductive stirring exhib its a 1.5(th) order dependence with respect to the nitrogen concentration i n the melt regardless of oxygen content. The rate of nitrogen desorption is controlled by three mixed rate-controlling steps of gas- and liquid-phase mass transfers and chemical reaction at the gas-metal interface and mainly by the latter two steps. It was deduced that the decrease of the nitrogen d esorption rate which accompanies the increment of oxygen concentration was mainly attributed to the attenuation of Marangoni convection and the increa se of chemical reaction resistance at the interface in the present study.