Deoxidation of molten iron with magnesium vapour produced in-situ by carbothermic reduction of magnesia

A new method of deoxidation of molten iron has been developed with magnesiu m vapour produced in-situ by carbothermic reduction of magnesia. Pellets of magnesia and carbon powders were charged into an alumina porous tube, whic h was immersed into the iron melt. The tube had one hole of I mm in diamete r, through which Mg vapour and CO gas produced by the carbothermic reductio n of MgO were injected into the melt together with At carrier gas. The part ial pressure of Mg vapour in the injected gas bubble changed with pellet ma ss, temperature and Ar carrier gas flow rate. The deoxidation rate increase d with increasing pellet mass and temperature. The deoxidation product MgO floated up to the free melt surface with the bubble and also reacted with A l2O3 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 s ome extent. A mathematical kinetic model of the deoxidation with Mg vapour was construc ted. The amount of oxygen reacted with Mg is greater during the bubble form ation period than during the bubble ascent period. At higher oxygen concent ration, the overall deoxidation rate is controlled by the Mg vapour supply; i.e., the rate of carbothermic reduction of magnesia, while at lower oxyge n concentration by the mass transfers of Mg vapour in the bubble and oxygen in the melt.