Dynamic free lance for slagmaking and steelmaking desulphurization

The dynamic free lance, discovered accidentally in 2005, is a new type of injection lance with its top-end connected with a flexible joint so that the lance tip could move during the gas injection. Without mechanical driving apparatus, the free lance is capable of injection of reagent into wide space of the bath. The investigation of the free lance indicated that the lance movement caused forceful interaction of the injection gas with the liquid phase, and jet trajectory was changed due to the drag force from the liquid phase. A lance with weight of 15 kg and length of 2 m has been used as the free lance for modeling study, indicating that the heavy free lance for the industry could achieve certain extent of movement for dispersion injection, and this prediction has been proved in 2012 by industrial application of the 9 meters free lance used for the injection modification of end-slag from BOF converter. In 2013, a stationary refractory lance with weight of 2 t for 120 t ladle of steelmaking desulphurization has also been redesigned and converted into the dynamic free lance with initial tests exhibiting the lance movement.