Electronic States of Oxygen Ions of Molten Slags Used for Iron and Steel Making.

Abstract

Abstrart Regarding molten slags used for iron and steel making, discrete anion models, SiO 4 − 4 and Si 2 O 7 6 − , coordinating metal ions such as Na + , K + , Ca 2 + and Mg 2 + were examined by the D V-X α method. The bond order which is a measure of the covalent bond and the ionicity which is a measure of the charge transfer were calculated. The bond orders between the Si ions and non-bridging oxygen ions were found to be very high. On the other hand, the bond orders between the Si ions and the oxygen ions coordinating the metal ions were very low, that is, the covalent bonds between them are weak. The metal ions such as Na + , K + , Ca 2 + and Mg 2 + are necessary for the formation of the free oxygen ions as well as the decomposition of polymerized structures. As a result, the bond orders between the Si ions and the oxygen ions coordinating the metal ions were found to be correlated with reactivity such as sulphide capacity of molten slags. The values of ionicity of the non-bridging oxygen ions were -1.0 ~ -1.4. These values of non-bridging oxygen ions are approximately equal to the valences obtained from the statistical thermodynamics studies.