Desulfurization by Powder Top Injection Process in RH Degasser

摘要

1. In the constant conditions of steel grade, desulfurizer and top slag in the ladle, the RH powder top injection process is faster and more efficient than the RH process in rate and efficiency of desulfuration, and improving the powder size and the agitation in reaction zone is effective on accelerating desulfurization. While lowering the desulfurizer consumption, some ultralow sulfur steels have been produced in which sulfur content can be 0.0010 mass percent or less. 2. The operating data show that the desulfuration rates of the RH powder top injection process can been described by a second order differential equation established by present work for changes of sulfur content in the ladle with time, which considered the apparent equilibrium concentration of desulfuration reaction, the mixed mass transfer of diffusion and circulation, and also included the effect of flux consumption on desulfuration efficiency. 3. Desulfationn effect is also dependent on the reaction characteristics with the mixture between flux and molten steel. On the condition that the mass transfer of a mixing control is caused together by both the diffusion and circulation, this mixing behaviours will play an important role in the desulfurating process with circulation flow system. 4. The observed values for apparent desulfuration reaction rate constant fell into a mixed mass transfer control zone of the circulation and diffusion. In conditions of the same circulating strength, this phenomenon of accelerating desulfuration reaction was observed in the powder top injection, It was related with powder injection penetrating the surface of molten steel in the vacuum vessel, which improved both reaction interface area and agitation in the reaction zone. In order to make a further improvement of the reaction rate, it hereby is necessary to take the comprehensive measures which can enlarge the circulation flow rate and the reaction interface area according to the equipment conditioin.