THERMODYNAMICS AND KINETICS OF NITROGEN ABSORPTION BY MOLTEN METAL OUT OF GAS PHASE

摘要

The problem on the most probable meaning of the nitrogen equilibrium constant has not been solved in the theory of nitrogen interaction with molten iron alloys, therefore, the numerous thermodynamic data are incompatible and do not permit the construction of the single thermodynamic model. Recommended is the following equation obtained as a result of measurements within the temperature range of1000K:1gK_N=-(850/T)-0.905The velocity constant of the surface adsorption reaction - nitrogen dissociation for mixed metal is mote than 100 times greater than for the immovable metal. The currently available theory of adsorption is not able to describe these facts; consideration must be given to the surface hydrodynamics. The model of nitrogen dissolution in molten metal is offered; the mass-transfer coefficient in this model is beta_0/zeta r_(eq)~(3/2)=1.6 centre dot 10~(-3)cm~(1/2) centre dot s~(-1) in case of nitrogen injection into metal through the lance and beta_0/zeta r_(eq)~(3/2)=3.6 centre dot 10~(-4)G~(1/3) in nitrogen injection through the porous plug for units with the mass G of up to 350 t.