Behavior of Nitrogen During AOD Process

Interfacial Phenomena in Metal–Slag–Gas System during AOD Process

“…(6) based on the estimation of contents of surface active elements during AOD process. 17) Simulations show that there are no possibilities to form metal film around the gas bubbles when they penetrate through the metal-slag interface. It is also independent of reaction intensity between the slag and the steel.…”

Modelling of the Refining Processes in the Production of Ferrochrome and Stainless Steel

“…In order to control the nitrogen content of the metal, it is necessary to know what is the effect of process variables on the nitrogen pick-up (during the stages in which nitrogen is blown into the system) and nitrogen removal (during the stages in which argon is used). (Heikkinen et al, 2007;Kärnä et al, 2008;Riipi et al, 2009) Unlike the oxidation and reduction reactions which can be modelled using computational thermodynamics with tolerable accuracy, a thermodynamic model, that describes the effects of metal compositions and partial pressures of nitrogen in the gas bubbles on the nitrogen solubility of the stainless steel melts, is not sufficient for the modelling of nitrogen. Although it is important to recognize chromium's increasing effect and nickel's decreasing effect on the nitrogen solubility, it is necessary also to model the mass and heat transfer in the gasmetal systems.…”

Law of Mass Action Based Kinetic Approach for the Modelling of Parallel Mass Transfer Limited Reactions: Application to Metallurgical Systems

“…A well-known example is the de-nitrification reaction of liquid steel. 9) The boundary condition for the rate expression of a single mass transfer limited reaction can be determined directly with the equilibrium constant method. One of the first qualitative descriptions of the boundary layer theory was proposed by Nernst 10) in 1904.…”

“…The final surface composition can only be obtained after solving the system of non-linear equations defined by Eqs. (9) and (10), which include the mass transfer rates. It is important to understand that the composition solved at the reaction interface is not the full chemical equilibrium that can be determined with traditional methods, such as the equilibrium constant method or Gibbs energy minimization, but rather a constrained chemical equilibrium: the equilibrium permitted by the mass transfer rates onto and from the reaction interface.…”

“…The rate expression is written here using the law of mass action for Eq. (9). For the sake of simplicity it is assumed that the transport rate or the amount of oxide species is not rate-controlling; the activities of the oxides were treated as constants.…”