Thermodynamic assessment of Mg deoxidation reaction of liquid iron and equilibria of [Mg]-[Al]-[O] and [Mg]-[S]-[O]

The deoxidation reaction of magnesium was investigated thermodynamically em ploying the equilibrium system between magnesium vapour and liquid iron in the molybdenum chamber sealed with an iron cover at 1873 K as a fundamental study to address the clean steel production technology in the steelmaking process. The previously reported thermodynamic data for magnesium deoxidati on reaction are limitedly in good agreement with only their respective spec ific Mg concentration range, but fail to explain the thermodynamic equilibr ia generally over the wider range of magnesium concentration beyond the lim ited range. Therefore, the equilibrium constant, K-Mg for the magnesium deo xidation reaction as well as the first and second-order interaction paramet ers between magnesium and oxygen were determined over the extensive magnesi um mass content range covering up to 0.04 %. Furthermore, the phase stabili ty diagram based on the equilibria of [Mg]-[Al]-[O] in liquid iron for the purpose of controlling the oxide inclusions in the steelmaking process was accomplished using the determined thermodynamic parameters. The equilibria of [Mg]-[S]-[O] were also discussed in order to evaluate the utilisation of Mg as a desulphurizing agent as well as deoxidizer in the production proce ss of low carbon steels.