Continuous Casting Process--6. What is a "cold" package? 7. What are the requirements for continuous casting tundish ?

 6. What is a "cold" room bag?

The tundish for continuous casting is usually built with firebrick, the working surface is coated with a layer of fireclay and then baked to about 1100c with gas for pouring steel. In recent years, the lining of the tundish is inlaid with block heat insulation board instead of firebrick, so there is no need to bake before use, so it is called "cold" tundish. Production practice has proved that "cold" tundish has the following advantages:

The baking bag is saved and the gas is saved, which is equivalent to saving 5.7kg standard coal per ton of billet;

For example, the shell temperature of insulating board tundish reaches 70c after pouring for 3 hours, while that of bricklaying tundish reaches 150C after pouring for 1 hour. In this way, the tapping temperature can be reduced by 5 ~ 10C, which is beneficial to improve the converter life;

The erosion of brick joint and refractory is reduced, which is beneficial to improve the quality of steel; Improve working conditions, reduce labor intensity, tundish insulation board repair is simple, after cooling insulation board powder, easy to make residual steel and lining separation, cleaning is very convenient.

7. What are the requirements for continuous casting tundish ?

If the molten steel is poured into the mold directly from the ladle, it will have adverse effects on the control of pouring operation and the quality of the slab. Therefore, an intermediate container must be set up between the ladle and the mold to receive the molten steel from the ladle, and then pour it into the mold at a stable flow rate. The functions of tundish are as follows: the storage of molten steel, controlling the amount of steel injected into the mold; For the distributor of molten steel, several nozzles are installed at the bottom of tundish to carry out multi-flow casting; The buffer of molten steel makes the pressure of molten steel stable and the steel flow stable; The molten steel cleaner can make the molten steel stay in the tundish for a period of time (e.g. 5 ~ 10min), which is conducive to the floating of inclusions and mixed slag droplets in the molten steel; Multi furnace continuous casting can be carried out to create conditions for ladle replacement. The tundish capacity is generally 20 ~ 40% of the ladle capacity. In order to improve the quality of steel, tundish is developing towards a large volume deep melting pool. For example, in some slab continuous casting, the intermediate capacity is 90t and the molten steel depth is 1300mm.

The duration should not exceed 1 min. Therefore, it is necessary to strengthen cooperation to make the tapping frequency of the steelmaking furnace adapt to the casting speed of the continuous caster so that the production can be carried out rhythmically. It is also necessary to strengthen the maintenance of equipment, strictly operate the rules, and prevent the occurrence of equipment and man-made accidents.

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Daisy Zhai