2015 Volume 55 Issue 7 Pages 1398-1407
The effects of three flux addition methods on hot metal desulfurization with mechanical stirring were investigated in a 1/12-water model test and a 70 kg hot metal desulfurization test. The flux addition methods studied here were top addition on the bath surface in the first period of desulfurization (batch addition), continuous addition from the top, and powder blasting with nitrogen gas. The desulfurization rate when powder blasting is applied is larger than that of either continuous addition or batch addition. The obtained aggregated slag (desulfurization flux) particle diameters after desulfurization were 0.76 mm (batch addition) and 0.38–0.44 mm (powder blasting). Desulfurization behavior was analyzed assuming that the interfacial area between the flux and the hot metal is proportional to the estimated size of the aggregated slag. Based on this analysis, the effect of powder blasting with nitrogen gas on improvement of desulfurization efficiency was interpreted to be the combined result of a) promotion of flux dispersion and avoiding aggregation during flux addition and b) prevention of slag particle aggregation in the hot metal during stirring.