The converter’s sliding plate slag-blocking technology, currently the most widely used and challenging, is used for steel tapping in converters. The refractory material in this system primarily consists of five components: the taphole brick, inner nozzle brick, upper slide, lower slide, and outer nozzle brick. The converter slide is a key component in this technology. The taphole, inner nozzle, slide, and outer nozzle bricks form the inner holes of the slide, which is activated by the movement of the slide.
The problems and disadvantages of refractory materials are as follows:
1.The service life of the skateboard is relatively low
At present, aluminum zirconium carbon is mostly used as the ladle slide material in China. As the ladle slide material, it has high strength, good thermal shock resistance, erosion resistance and corrosion resistance. However, for the converter slide slag blocking technology, the slide has a short service life and can only be stable between 10 and 14 furnaces. It is basically replaced once per shift, and the number of mechanism replacements is relatively high. To a certain extent, it cannot meet the needs of the fast-paced steelmaking production of the converter, and it also increases the labor intensity of workers.
2.Export life needs to be further improved
The outlet life is a key indicator of converter slide slag retention technology. Frequently subjected to direct erosion and intense erosion from high-temperature molten steel and highly oxidizing slag, coupled with rapid cooling and heating, the outlet is highly susceptible to damage. Its service life directly impacts the converter’s smelting cycle, steelmaking productivity, and slag retention, ultimately affecting steel quality. The integrity of the outlet directly controls the converter’s slag discharge, which in turn directly affects alloy yield and subsequent refining processes (LF, RH, etc.).
Currently, service life is stable at 90-110 furnaces, but achieving a higher service life is difficult. The core issue is that the taphole and inner nozzle bricks are bonded together via a flat surface or a chuck-and-duck joint, which is in surface contact. This contact surface is highly susceptible to air infiltration during use. Frequent replacements can lead to oxidation, loosening, and flaking of the contact surface, particularly at the taphole-inner nozzle contact (end C brick). Because multiple sets of inner nozzle bricks are used, the effects of oxidation and loosening are even more pronounced. Therefore, the service life of the taphole end C brick has become a key factor in determining the longevity of the taphole.
Measures to improve refractory application
1.Improve and optimize the material and structure of the skateboard to greatly increase the service life of the skateboard.
2.Measures to improve the overall life of the taphole
During the converter tapping process, molten steel flows through the outlet into the ladle. Under the impact of the high-temperature flowing steel, the outlet refractory material gradually melts, expanding the outlet’s inner opening into an inverted trumpet-shaped pattern (smaller at the top and larger at the bottom). Because the outlet is composed of a monolithic assembly of shell bricks and end bricks (C bricks), the outlet C bricks cannot be replaced individually during actual use. After 90-110 furnaces, even if the inner outlet bricks are replaced, the expanded hole of the outlet C bricks is too large to ensure a secure bond with the inner outlet bricks, resulting in a high risk of leakage at the interface. In this case, the entire outlet must be replaced immediately, while the remaining shell bricks in the converter ladle wall can continue to be used. This significantly reduces the outlet’s overall lifespan, increasing the frequency of replacements, impacting normal production organization and capacity, and increasing the cost of the outlet refractory material.
The new design replaces the monolithic C bricks with a modular structure, using individually replaceable bodies (bowl bricks) in the expansion area. The taphole C bricks adopt a new structure. When the taphole C brick is enlarged to the point where it cannot ensure a safe bonding area with the inner nozzle bricks, the taphole C bricks are replaced separately as a combination of bricks. This ensures a safe bonding area between the taphole C bricks and the inner nozzle bricks and continuously improves the taphole life by 20% to 40%. This measure effectively increases the online service life of the taphole from the original 90 to 110 furnaces to 120 to 140 furnaces, and greatly improves the safety factor of steel pouring in this area.