Corundum spinel refractory castables have excellent slag resistance, spalling resistance, low melting loss, long service life, high safety and other advantages, which can meet the smelting process of the electric furnace round and square billet production line; its damage is mainly caused by the reaction between slag and refractory materials, and thermal stress and mechanical stress also play an important role.
The main differences between the cast ladle bottom and the brick-built ladle bottom:
1) The turnover time of the cast ladle bottom is about 24~38h, the construction time is 2h, the maintenance time is 16h, and the baking time is 36h; the construction time of the brick-built ladle bottom is 4h, and the baking time is 12~24h.
2) Maintenance mode adjustment, when the brick-built ladle is repaired, the entire ladle bottom working lining needs to be replaced, including the ladle bottom alumina-magnesia-carbon bricks; while when the cast ladle is repaired, only the air bricks, nozzles and impact areas need to be replaced.
The corundum-spinel refractory castable was applied to the working layer of the 150t ladle bottom of Baosteel's electric furnace billet production line (13# and 8# ladle), with a water addition of 5.0%~5.5% (w), a flow value of 180~220mm, a stirring time of 3~5min, and a vibration rod for exhaust. The total construction time was 1~2h.
The service life of the two casting ladle bottoms during overhaul was 92 furnaces and 91 furnaces (normal offline). There were only slight cracks on the casting ladle bottom during use. The most severely damaged area during overhaul was the impact area of the ladle bottom, but the residual thickness was >100mm. The entire ladle bottom working layer was replaced during the mid-repair of the brick-built ladle bottom. It can be seen that the corundum-spinel refractory castable can meet the use conditions of the ladle of the electric furnace billet production line and has a better service life.
Compared with the brick-built bottom, the integral casting of the ladle bottom has the following advantages:
1) The brick joints of the bottom working layer are reduced, which reduces the probability of cracking of the bottom and cold steel seeping along the brick joints, and improves the safety of the ladle.
2) The air tightness and integrity of the bottom working layer are strengthened, the probability of "side blowing" of the air-permeable bricks is reduced, and the probability of offline due to abnormal air-permeable bricks is reduced, and the safety is improved.
3) In the middle and late stages of use, there will be no abnormal falling of bricks due to the gradual increase of brick joints.
4) Mechanical construction is easy to operate and reduces labor intensity.
5) There is no need to replace the entire bottom working layer during the mid-repair, and the bottom impact zone is maintained with repair materials, which reduces the consumption of refractory materials.
