Effects of operating parameters on desulfurization of molten iron with magnesium vapor produced in-situ by aluminothermic reduction of magnesium oxide

The effects of operating parameters on desulfurization of molten iron with magnesium vapor produced in-situ by the aluminothermic reduction of magnesium oxide have been studied. To promote the reduction of magnesium oxide and to make use of the heat of the molten iron, a refractory tube charged with the pellets that were made of the mixture of magnesia and aluminum powders, was immersed into the melt. The produced magnesium vapor was injected directly into the melt with Ar or N-2 carrier gas to react with sulfur in it. Compared with using Ar, using of N-2 as the carrier gas resulted in lower desulfurization efficiency due to a part of aluminum reacting with N-2 to form AlN. Increasing the pellet forming pressure promoted the reduction of magnesium oxide, and hence improved the desulfurization efficiency. The use of a porous Al2O3 or MgO tube decreased the desulfurization rate as compared with that of a dense graphite tube. In the case of the porous Al2O3 tube, the magnesium vapor reacted and/or was adsorbed with the porous Al2O3 tube in the initial stage of the experiment. The reverse reaction and/or the desorption took place to produce magnesium vapor in the later stage of the experiment. In the case of the porous MgO tube, the magnesium vapor was adsorbed and desorbed by the tube during the experiment. When the dense Al2O3 tube was used, a horizontal nozzle was installed to improve the desulfurization efficiency. It is possible to enhance the desulfurization efficiency of pellet by dividing pellet charging into two portions. As the oxygen partial pressure in the atmosphere was increased, the desulfurization efficiency became low and the resulfurization reaction became more noticeable in the later stage of the experiment.