Cleansing the molten steel due to the dispersed in situ phase induced by the composite sphere explosion reaction II. Inclusion removal

Industrial trials have been carried out on the base of the former experimental research and the CaCO₃ proportion in composite sphere, feeding amount, and composite sphere feeding mode have been investigated. The fine inclusion removal mechanism has been analyzed. The results indicate that feeding composite sphere in RH degasser is a novel process and small inclusion in the molten steel can be removed effectively. CaCO₃/CaO ratio in composite sphere has a great effect on the inclusion removal efficiency. More feeding times and a little feeding amount can increase the composite sphere utilization efficiency. Compared with the conventional inclusion removal technology, the number density of the oxide inclusion can be decreased to a lower level and the inclusion size becomes much finer. Using this novel process, T.O. in the as-cast slab can approach to 6 ppm.