When dismantling the used furnace lining, it was found that the damage was caused by the unusability of some severely eroded parts, while many other parts, although usable, had to be abandoned in order to build new furnace linings. Therefore, people proposed the concept of comprehensive furnace building and balanced furnace lining, that is, selecting furnace lining bricks of different qualities according to the erosion state of different parts of the furnace lining.
The temperature of the furnace mouth changes dramatically, and it is severely eroded by slag and high-temperature exhaust gas. Therefore, the refractory bricks used for the furnace mouth must have high thermal shock resistance and slag resistance.
The furnace cap area is mainly eroded by the gas in the furnace and the splashing of slag during blowing. It is also affected by the sudden change of temperature and the erosion of dusty exhaust gas. Therefore, magnesium carbon bricks with strong slag resistance and good thermal shock resistance should be used.
The lining bricks in the furnace wall area, especially the lining bricks on the charging side, are eroded by molten steel and slag, and require high high-temperature strength.
The slag line and trunnion area are the most demanding parts of the converter lining. They are eroded and corroded by molten steel and slag, as well as by the gas in the furnace. Therefore, bricks with the best corrosion resistance are required.
In the converter lining, the tapping hole brick is another brick with special significance. The tapping hole of a large converter has a large amount of steel and is eroded by molten steel. The service life is generally short, far lower than the life of the lining, so the tapping hole bricks must be replaced frequently. Tapping hole bricks can be divided into integral type and segmented assembly type in terms of style. At present, it is believed that the integral tapping hole of magnesium carbon has better use effect, long service life and convenient replacement.
In the smelting process, due to the different working conditions of each part, the corrosion of each part of the working layer is also different. Our company adopts a comprehensive masonry method to achieve balanced erosion of the overall lining. For comprehensive masonry, 3-6 bricks of different grades should be selected according to the specific conditions of different manufacturers, and they should be masonried in the slag line, trunnion, furnace wall, molten pool and other parts respectively, in order to obtain the best economic benefits.
According to the above requirements, the configuration scheme of refractory materials for a 180t converter in a steel plant is shown in Figures 1 and 2.
As shown in Figure 1: ① At the furnace mouth and furnace cap: the permanent layer is built with non-standard bricks, the working layer is built with 500-650mm thick magnesia carbon bricks, and the furnace mouth and the furnace shell are tied with castables; ② Furnace body: the permanent layer is built with 1 layer of 115mm thick sintered magnesia bricks, and the working layer is built with 650mm thick magnesia carbon bricks; ③ Molten pool: the permanent layer is built with 1 layer of 115mm thick sintered magnesia bricks, and the working layer is built with 700-750mm thick magnesia carbon bricks; ④ Furnace bottom: the permanent layer is built with 2 layers of 75mm thick sintered magnesia bricks, and the working layer is built with 750mm thick magnesia carbon bricks.