Desulfurization of molten iron with magnesium vapor produced in-situ by aluminothermic reduction of magnesium oxide

Magnesium vapor produced in-situ by aluminothermic reduction of magnesium oxide was injected directly into the melt with argon carrier gas to desulfurize molten iron to an ultra-low sulfur concentration in a short time. The desulfurization rate increased with increasing temperature in the range from 1 553 to 1 773 K. The desulfurization efficiency of pellet increased with decreasing pellet mass. The effects of initial sulfur concentration and carrier gas flow rate on the desulfurization were also investigated. A mathematical model is developed to calculate the desulfurization rate and good agreement is obtained between calculated and experimental results. The calculated results show that when the initial sulfur concentration is not very high, the mass transfer rate of magnesium in the bubble is faster than that of sulfur in the melt. The amount of desulfurization during the bubble ascent period is 3.5-9.3 times larger than that during the bubble formation period. Effects of the pellet mass and the initial sulfur concentration on desulfurization can be well explained by the present mathematical model.