Main conditions of rational technological solutions of injection processes for ladle desulphurization of hot metal by various dispersed reagents

Abstract

Application of dispersed reagents in hot metal ladle treatment processes enabled for solving a wide range of tasks of increasing metal products quality and improving technical and economic indices of metal smelting processes. But there are reserves of existing technologies improving, since during their application a whole number of peculiarities of heat- and mass exchange processes, having place in ladle at wide range of parameters and refining conditions, are not taken into consideration. Therefore, elaboration of conceptions about exchange processes mechanisms at different reagents injection input and elaboration of most rational technological solutions are rather actual.Influence of chemical and fraction-dispersed content of reagents on hot metal desulphurization processes studied. First priority of CaO and Mg application justified.It was shown, that when using fine powders, particles less 0.08 mm practically do not penetrate into hot metal melt, and when grain reagents (0.2–1.6 mm) are used, their particles can penetrate into hot metal by a depth of 25 mm.It was established that during the injection desulphurization there are conditions and separation of blow-in two-phase stream takes place in near-tuyere zone with division for gas and solid components.During the desulphurization by powder non-magnesium reagents (lime), the powder concentration 40–60 kg/Nm3 in gas justified, usage of reducing agents not from hot metal components (С, Si, Mn), but Al introduced from outside. Besides, it was recommended to introduce evaporating and gas-forming (in the melt) additions into gas and solid phase for additional phase dispersion in the neartuyere zone.During the magnesium mono-injection its application in the form of grains (0.2–1.6 mm) justified and blow-in velocity >80 m/s.The obtained scientific preconditions of hot metal desulphurization efficiency increase by different reagents were checked in industrial conditions.