Composition of Refractory Materials in Slide Plate Slag Stopping Systems

Using slide plates to stop slag in converter tapping is one of the most advanced methods internationally, yet also the most challenging slag stopping technology. Using this technology, the system’s refractory materials primarily consist of five refractory components: the taphole bricks, inner nozzle bricks, upper slide plate, lower slide plate, and outer nozzle bricks. The converter slide plate is one of the most critical components in this technology. The taphole, inner nozzle, slide plate bricks, and the inner holes of the outer nozzle bricks form the tapping channel, while the movement and opening of the lower slide plate achieves slag stoppage. Conventional refractory materials in slide plate slag stopping systems.

Major Issues in Refractory Application

Consumer converter slag stopping technology is still in its infancy in China. The refractory materials, equipment, and replacement techniques required for this technology require continuous improvement and optimization. The following are the main refractory issues and shortcomings currently hindering the development of this technology.

1) Relatively Short Slide Plate Life

Currently, aluminum-zirconium-carbon is the most common material used for converter slide plates in China. As a ladle slide plate material, it offers high strength, excellent thermal shock resistance, and excellent erosion and corrosion resistance. However, for converter slide plate slag containment technology, the slide plate life is relatively short, only stable at between 10 and 14 furnaces, essentially requiring replacement once per shift. This frequent mechanism replacement is, to a certain extent, unsuitable for the fast-paced converter steelmaking process and increases worker workload.

2) Taphole Life Needs Further Improvement

Taphole life is a key indicator of converter slide plate slag containment technology. Frequent exposure to direct erosion and intense erosion from high-temperature molten steel and highly oxidizing slag, coupled with rapid cooling and heating, makes the taphole susceptible to damage. Its lifespan directly impacts the converter’s smelting cycle, steelmaking productivity, and slag containment effectiveness, ultimately affecting steel quality. The integrity of the taphole directly controls the amount of slag discharged from the converter, and has a direct impact on alloy yield and subsequent refining processes (LF, RH, etc.). Currently, the service life is stable at between 90 and 110 furnaces, but it is difficult to break through the bottleneck of a longer service life. The core problem is that the connection between the taphole and the inner nozzle brick is a flat surface or a mother-and-child contact structure bonded by fire mud. The contact area is in surface contact, and the probability of air infiltration in use is relatively high. Due to oxidation, loosening and flaking of the contact surface caused by multiple replacements, especially the contact area between the taphole and the inner nozzle (end C brick) due to the need to use multiple sets of inner nozzle bricks, the impact of oxidation and loosening of the contact surface is more obvious. Therefore, the service life of the taphole end C brick has become the key to the longevity of the taphole.