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Concentration profiles of iron and sulphur in non‐stirred steel‐slag systems
Author(s) -
El Gammal Tarek,
Wosch Erwin,
Lim BoungMo
Publication year - 1995
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199501133
Subject(s) - chemistry , marangoni effect , mass transfer , convection , slag (welding) , diffusion , thermodynamics , viscosity , mass transfer coefficient , sulfur , metallurgy , analytical chemistry (journal) , chromatography , materials science , physics , organic chemistry
This investigation presents a mathematical, uni‐dimensional model for the description of measured concentration profiles of sulphur and iron in non‐stirred bath‐slag systems. Detailed analysis of the profiles in slags of several basicities show that the mass transfer is also influenced by a convective transport mechanism overlaying diffusion. The interfacial convection, known as the Marangoni effect, is considered to be the reason for this convection at the phase boundary. The dependence of the mass transfer on the basicity, the initial sulphur content of the bath, and the addition of a CaF 2 mass content of 2.5 % has been investigated. A computer calculated match of theoretical concentration plots with the data measured yields the interdiffusivity of S 2– and Fe 2+ within the slag, the average velocity of the convective material transport normal to the phase boundary, and the equilibrium sulphur contents. The value of the average velocity increases exponentially with decreasing slag viscosity. The relation between the mass transfer coefficients and both the diffusion coefficient in the bath and the interdiffusivity in the slag, familiar from the surface renewal theory, follows as a consequence of the mass conservation law.