1996 Volume 36 Issue Suppl Pages S69-S72
In the KCB-S process—a modified AOD process—process gases are blown into a metal bath through bottom tuyeres and onto the bath surface by a lance. Depending on the distribution of the gas volume flow rates to the two blowing devices, differing reaction spaces and reaction areas are formed.
The change in the reaction areas for nitrogen absorption and their ratio in the metal bath and on the bath surface, including metal droplets, has been determined from an investigation into the reaction kinetics of nitrogen absorption under modified blowing conditions.
The investigation was carried out in the final stage of lance use with carbon contents of between 0.5 and 0.2%. The composition and volumetric flow rate of the process gases was varied during the decarburization of AISI 304. The reaction areas increase as the volumetric gas flow rates rise. The reaction area of the gas bubbles is considerably greater than that of the metal droplets and the bath surface. Owing to the higher reaction rate of oxygen with the metallic melt, rising gas bubbles have a smaller reaction area for oxidation than for nitrogen transfer. Using the test technique presented here it is possible to optimize partial reaction areas and thus process control.