The ladle is automatically opened, which means that the ladle is used to prevent the molten steel from directly contacting the nozzle on the ladle before the molten steel is filled. So add drainage sand to the nozzle, when the sliding nozzle is opened, the molten steel can automatically flow out with the drainage sand.

When the nozzle of the ladle cannot be self-opening, it is necessary to use oxygen burning method to melt the drainage sand in the nozzle and let the molten steel flow into the tundish.

At the time of drainage, the molten steel will be oxidized again due to the addition of oxygen, and the quality of the molten steel is difficult to guarantee.

Increased the labor intensity of workers, at the same time, the cost of steelmaking has increased. And it may also threaten the safety of equipment and personnel.