Surface kinetics of nitrogen dissolution and its correlation to the slag structure in the CaO-SiO2, CaO-Al2O3, and CaO-SiO2-Al2O3 slag system

The kinetics of nitrogen dissolution into molten slag at 1873 K was investigated by an isotope exchange technique. Rate constants were correlated with the molten slag structure obtained from FT-IR spectra. The rate constant in the CaO-SiO2 binary system showed a maximum value at a specific slag composition followed by a decrease in the rate due to excess O2- blocking the surface sites for nitrogen adsorption. The rate constant in the CaO-Al2O3 binary system was comparatively constant within the experimental range of 45 mass% to 60 mass%. The rate constant in the CaO-SiO2-Al2O3 ternary slag system was measured within the boundary of the liquidus line and showed a close correlation with the slag structure. Furthermore, the rate constant in the CaO-SiO2-Al2O3 ternary system was found to be significantly higher compared to the binary system due to the correlated effect of lower binding energies of the Al-O bonds and the increased number of reaction sites available when smaller Si-O tetrahedral were simultaneously present with Al-O bonds. (C) 2011 Elsevier B.V. All rights reserved.