In the converter steelmaking, the normal feeding sequence is: scrap-molten iron, that is, first add a certain amount of scrap to the converter, and then start adding molten iron.
Adding scrap steel first is more from a safety perspective. First, the residual temperature in the furnace can be used to bake the scrap, evaporate the water vapor in the scrap, and reduce the hydrogen content in the molten steel from the source; the second is the scrap at the bottom of the furnace. The formation of a buffer zone is beneficial to reduce the impact of multiple additions of molten iron on the furnace bottom lining.
If the molten iron is added first and then the scrap steel is added, once the scrap steel is wet or mixed with water, because the density of the scrap steel is relatively high, it will sink after being added to the molten iron. Because the temperature of the molten iron is relatively high, the water is instantly vaporized to form steam, and the volume of the molten iron is rapid in a short time. Expansion will cause an explosion accident. This situation is quite dangerous. If the scrap is mixed with bombs, sealed containers, etc., the harm will be even greater. There is also a method of adding molten iron before adding scrap: mainly from the perspective of furnace protection. Ironing first can effectively reduce the impact of large scrap steel on the front lining of the converter, increase the life of the furnace lining, and reduce the use of scrap when smelting ultra-low carbon steel. The phenomenon occurs. The general principle is to protect the furnace from being damaged by scrap steel. When the scrap is heavier, the amount of bottom slag is not large, and the molten iron is added several times, the molten iron must be added first.
The two loading sequences need to be determined according to the actual site, and can be flexibly changed.