ABSTRACT In the present work, a new ladle dephosphorization process has been developed using the dispersed in situ phases induced by an explosive reaction of the composite balls with slag forming materials. A composite ball with this function has been designed and prepared using a laboratory model batch type balling disc (at 12 rev min−1) and then has been fed during the convert tapping process. The results indicate that the explosion reaction of a composite ball at steelmaking temperature can take place and plenty of fine powders have been released. Feeding composite ball during converter tapping is a new process and the phosphorus in the molten steel can be removed effectively. Using this technique, the average dephosphorization rate is about 50% and the lowest phosphors in the molten steel can approach 40 ppm. Furthermore, there is no phosphorus reversion phenomenon occurred after the following procedures. Further study is recommended.