2001 Volume 87 Issue 10 Pages 635-642
A new method of deoxidation of molten iron has been developed with magnesium vapour produced in-situ by carbothermic reduction of magnesia. Pellets of magnesia and carbon powders were charged into an alumina porous tube, which was immersed into the iron melt. The tube had one hole of lmm in diameter, through which Mg vapour and CO gas produced by the carbothermic reduction of MgO were injected into the melt together with Ar carrier gas. The partial pressure of Mg vapour in the injected gas bubble changed with pellet mass, temperature and Ar carrier gas flow rate. The deoxidation rate increased with increasing pellet mass and temperature. The deoxidation product MgO floated up to the free melt surface with the bubble and also reacted with Al2O3 of the immersion tube. The reoxidation reaction of Mg vapour by CO gas in the bubble occurred and the deoxidation efficiency of Mg decreased to some extent.
A mathematical kinetic model of the deoxidation with Mg vapour was constructed. The amount of oxygen reacted with Mg is greater during the bubble formation period than during the bubble ascent period. At higher oxygen concentration, the overall deoxidation rate is controlled by the Mg vapour supply; i.e., the rate of carbothermic reduction of magnesia, while at lower oxygen concentration by the mass transfers of Mg vapour in the bubble and oxygen in the melt.
