Introduction to ladle refiningedit

Out-of-furnace refining divides the traditional steelmaking into two steps. The first step is called primary smelting, which involves melting, dephosphorizing, decarburizing and main alloying of the charge in an oxidizing atmosphere; the second step is called refining, in a vacuum and inert atmosphere. Or deoxidize, desulfurize, remove inclusions, denature inclusions, fine-tune the composition, control the temperature of molten steel, etc. under a controllable atmosphere. Since the 1960s, various methods of refining outside the furnace have appeared one after another. This technology has been developed rapidly all over the world.

Out-of-furnace refining has become an indispensable link in the modern steel production process. In particular, the combination of out-of-furnace refining and continuous casting is an important means to ensure the smooth production of continuous casting, expand the variety of continuous casting, and improve the quality of slabs.

In the steelmaking production process, the use of converters (or electric furnaces)-refining outside the furnace-continuous casting has become a common mode of technological transformation in steel plants.

The processes of various out-of-furnace refining methods are different, and their common features are: there is an ideal refining atmosphere, such as vacuum, inert gas or reducing gas; electromagnetic force, blowing inert gas to stir molten steel; to compensate for the refining process The temperature loss of molten steel is reduced by heating methods such as arc, plasma, chemical method, etc.

Ladle refining matched with continuous casting is to improve the quality of the cast billet and ensure the stability of the continuous casting process. Choosing a suitable method of refining outside the furnace is an important means for preparing molten steel for continuous casting and providing qualified quality molten steel. For this reason, the selection of ladle refining equipment based on product quality requirements should meet the following basic requirements:

1. Adjust the temperature of molten steel to reach the pouring temperature range required by continuous casting;

2. Improve the cleanliness of molten steel, especially reduce the content of large inclusions in the steel;

3. Reduce the gas content in steel (such as hydrogen and nitrogen content); 

4. Reduce the content of harmful impurities (such as sulfur and phosphorus) in steel;

5. To homogenize the temperature and composition of the molten steel, and fine-tune the composition to make the chemical composition range of the finished steel very narrow;

6. Change the shape and composition of inclusions in steel to improve the fluidity of molten steel;

7. Reduce the smelting load of the steelmaking furnace, shorten the smelting cycle, and increase the productivity;

8. The ladle refining furnace becomes a "buffer" between the steelmaking furnace and the continuous casting machine to balance the production rhythm between the two, which is conducive to improving the productivity of the continuous casting machine.