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Before the ladle is officially filled with steel, after closing the sliding nozzle, use a long funnel to put drainage sand into the upper nozzle to prevent the molten steel from entering the upper nozzle and condensing. When the skateboard is turned on, the molten steel will drop immediately after the drainage sand drops to achieve the purpose of automatic pouring. Whether the ladle drainage sand can be self-opened is greatly related to factors such as the material of the drainage sand, the particle size ratio, and the length of the refining time. Drainage sand includes sea sand, river sand, refractory bricks and chrome ore in materials.
(1) Drainage sand has high density and high melting point. The particles are not easy to sinter, and the volume is stable at high temperatures;
(2) The shape of the drainage sand is spherical, without obvious edges and corners, with moderate particle size, the smaller the fine powder content, the better, and the particle size should be consistent;
(3) The smaller the natural pile angle, the better, the flow performance is good, and the surface is smooth for filling and scattering;
(4) In order to prevent molten steel from penetrating into the drainage sand, it is required that the molten steel has a greater interfacial tension on the drainage sand;
(5) Drainage sand has good corrosion resistance to molten steel and molten slag at high temperatures, and it is required that the drainage sand does not chemically react with the sliding nozzle near the bottom nozzle, and has good high-temperature physical properties;
6) Drainage sand must be dried before use, so that the moisture content is <0.5%