2006 Volume 92 Issue 4 Pages 246-253
The mechanism of resulfurization in the desulfurization process with magnesium vapor produced in situ by aluminothermic reduction of magnesium oxide was clarified in the present work. The influences of various operating parameters on the resulfurization were studied and the methods for preventing the resulfurization were proposed.
There are two kinds of mechanisms of resulfurization in the desulfurization process with magnesium. One is decomposition of the desulfurization product of MgS under the inert atmosphere. The other is oxidation of MgS under the oxidative atmosphere.
Under the present experimental conditions, lowering operating temperature and oxygen partial pressure in the atmosphere, and adding more pellets containing magnesium oxide and aluminum could effectively prevent the resulfurization. The resufurization took place more markedly by using Al2O3 crucible than by using MgO or graphite crucible.
Adding CaO onto the melt surface was an effective method for preventing the resulfurization due to transformation of the desulfurization product of MgS into the more stable compound of CaS. For prevention of the resulfurization, using the CaO-Al2O3 mixture is less effective than using only CaO. Since addition of the activated charcoal powders greatly decreased the transfer rate of oxygen in the atmosphere to the melt surface and the oxygen partial pressure on the melt surface, it also prevented the resulfurization effectively.
