The development of study of the kinetics and oxidation of molten iron impurities using the critical concentrations as the base

A new approach to the assessment of the ?critical? concentration of impurities in metallurgical melts has been put forward by the author. The inapplicability of the traditional method of their calculation, based on kinetic studies of oxidation processes for the elements, the affinity with oxygen of which is lower than that of the base metal melt has been shown. The nature of the oxidation process when the impurities concentration is above the critical concentration, has been ascertained, a great number of laboratory and field data having been used. It has been proved experimentally using the developed installations that oxidation of arsenic hardly occurs in real metallurgical melts. There is a concentration gradient as to the mo-lecular and convective diffusion, providing for the transfer of the reacting components in steel tubs. The kinetic equation for the oxidation of impurities at concentrations below the ?critical? concentration has been shown. An attempt was made to determine the ?critical? concentration of arsenic; arsenic being one of those elements, chemical affinity with oxygen of which is higher than that of iron; it forming volatile oxides. The author managed to show that in case the concentration of arsenic in the melt Fe-As is critical iron becomes the oxidizing component and it is its ?critical? concentration that should be determined. Kinetic curves of impurities’ oxidation in ?concentration ? time? coordinates have been built. The ?critical? concentration of solvent metal can always be determined from the beginning of the oxidation process retardation. The data obtained in the refining of arsenic-bearing conversion pig iron at the steel works ?Azovstal? have been listed. Critical concentration of arsenic is possible and can only be detected under certain conditions of the oxidating refining, that provides for the transition from the surface of the reaction to gaseous As2О3