Simultaneous Absorption of Nitrogen, Oxygen and Carbon of Liquid Iron from N₂-CO₂and Ar-CO₂Gas Mixtures

Abstract

The rates of simultaneous absorption of nitrogen and oxygen in liquid iron from argon-carbon dioxide and nitrogen-carbon dioxide gas mixtures were measured.
Carbon dioxide has little influence on the rate of absorption of nitrogen in liquid iron when the gas phase containes carbon dioxide lower than 7·2vol pct. However, above 10vol pet, the absorption rate of nitrogen decreases due to the oxygen concentrated layer at gas-metal interface.
The results show that the rate of absorption of oxygen from carbon dioxide increases with increasing partial pressure of carbon dioxide. On the other hand, it is also observed that the concentration of carbon in liquid iron increases at early period of reaction, and then decreases after several minutes for every gas mixture.
Considering the dissociation of CO₂into CO and atomic oxygen, the rate limiting steps of oxygen absorption may be gaseous diffusion control below 3 vol pct carbon dioxide, chemical reaction control at the interface in the range between 3 and 15vol pct, and diffusion control in liquid iron above 15vol pct. There are practically no difference between the mechanism of absorption of oxygen by nitrogen-carbon dioxide and argon-carbon dioxide gas mixtures.
The behavior of carbon in liquid iron may be determined by combining the carbon absorption from carbon monoxide with the decarburization by gaseous oxygen atom.