Abstract
Experimental study of desulfurization reaction by pulverized CaO impinging upon steel melt in a vacuum vessel of a RH degasser was carried out to disclose the effects of powder and operation factors.
Experiments were carried out by NO. 2 RH degasser at Mizushima works of Kawasaki Steel Corporation. Powder was blasted on steel melt in the vacuum vessel through KTB (Kawasaki Top oxygen Blowing) with a single hole. The powder was penetrated into steel melt and transferred to a ladle except powder directly drawn by suction through an exhauster. Powder size, powder feed rate and slag composition in a ladle were changed for the experiments. Initial sulfur content was 25-35 mass ppm.
Sulfur content after the pulverized CaO blasting treatment reached below 10 mass ppm. Desulfurization ratio increased as the CaO unit consumption increased while the (MnO)+(T.Fe) and the oxygen activity in molten steel decreased. Because too small powder size caused the decrease in yield and too large size decreased the desulfurization rate, an optimal powder size existed for desulfurization efficiency.
