The setting of the purging plug brick is determined by the size of the molten steel in the ladle, the quality requirements of the stirring function for the smelting steel grade and the process route. When choosing the location of the bottom blowing component of the ladle, it should be determined according to the purpose of ladle treatment. The air-permeable bricks are installed at the center of the ladle bottom and away from the center of the ladle (the air blowing point is at a radius of 1/2~1/3 from the center of the ladle bottom). The stirring effect of air blowing on molten steel is different. The reaction between gold is beneficial to the desulfurization reaction of the top slag; while the eccentric bottom blowing argon is beneficial to the mixing inside the ladle, the homogenization of temperature and the floating of inclusions. For example, the purging plug bricks of CAS/CAS-OB need to be installed at the center of the bottom of the ladle, because the process requires argon to blow off the molten steel slag surface under the dipping hood to meet the requirements of alloying or oxygen spraying during smelting. The LF furnace process requires that the purging plug bricks be installed near the bottom of the LF furnace door to meet the requirements of carbonization, alloying and deoxidation during smelting. The more ladle purging plug bricks are installed, the more small bubbles are generated, the more obvious the effect of removing inclusions, and the better the quality of molten steel. However, the greater the number of installations, the greater the risk of steel leakage. Usually, when smelting ordinary carbon steel, one purging plug brick can be used for the ladle below 70t; two purging plug bricks need to be used for the ladle larger than 70t.
The installation form of the ventilation brick can be built-in and external. The built-in type refers to the pre-assembly of the purging plug bricks and the seat bricks outside the ladle. When building the ladle, clean the position of the purging plug bricks at the bottom of the bag, and hoist the purging plug bricks with the seat bricks to this position after building the curtain bricks. , and then build the bottom of the bag and the lining in turn. The exterior type consists of seat bricks, cover bricks and ventilation bricks. When laying the ladle, the bottom of the bag and the wall of the bag can be built after the seat bricks are installed at the bottom of the bag, and then the outer sides of the cover bricks and the air-permeable bricks are evenly coated with fire mud, and then forcefully put into the seat in turn, and then the cover bricks and The bottom of the ventilation brick is sealed with a cushion brick, covered with a flange, and baked. The built-in purging plug brick is used in the case where the lifespan of the ladle lining brick and the purging plug brick are synchronized, while the externally installed type is suitable for the situation where the purging plug brick needs to be replaced frequently. Due to the low safety, poor reliability and troublesome replacement of the built-in purging plug bricks, at present, almost all ladles use the externally-installing purging plug bricks.
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