In the converter steelmaking production, due to the large amount of molten steel slag produced during the smelting in the furnace, the traditional slag blocking process uses the slag ball to discharge the slag. Since the Slag Ball usually arrives at the taphole in a wave-by-flow manner, and because the steel slag is very viscous, the slag ball cannot reach the taphole, or can not effectively block the taphole when the molten steel is exhausted, and the slag ball is usually efficient <75%. It adopts Slag Dart tapping, its shape is conical, and there are three flow steel channels on the outer side: the effective efficiency of slag blocking can be increased by ≥90%, the slag layer is ≤50mm, and the slag of ton steel is about 3-5 kg, for increasing steel production And the purity of steel, improving steel and mechanical properties have a very significant effect. At the same time, it can improve the production efficiency of converter steelmaking, reduce energy consumption, and reduce the environmental pollution of the platform after the furnace. It is easy to operate and safe to use. This new process significantly reduces energy consumption, reduces the temperature loss of molten steel, and increases the safety of steelmaking operations.