Abstract
In order to enhance the dispersion of desulfurizing agents into hot metal, the injection of nitrogen gas has been used together with the revolutional stirring by an impeller of a gate type. At the both ends of the impeller, a nozzle is embedded and used for the injection of nitrogen gas into hot metal toward the direction opposite to the movement of the impeller.
Water model experiments show that the gas injected efficiently breaks up a cone shaped agglomerate of desulfurizing agents at the bottom of the rotational vortex formed around the impeller shaft and makes it disperse homogeneously into the bath. This suggests that the chemical efficiency of desulfurization will be improved to a greater extent than that without the gas injection.
The plant scale equipment has been constructed to desulfurize 60t of hot metal in a ladle. Under the condition of 77 rpm in revolution rate and 3 Nm3/min of nitrogen gas, sulfur content of 0.05% is reduced to 0.012% after the treatment of 1 1 min with calcium carbide of 3kg (75% in purity) per ton of hot metal.
The observed rate of desulfurization is reasonably interpreted in terms of the rate controlled by sulfur transfer in hot metal.
