Application and effect of magnesia carbon brick for refractory prefabricated parts

At present, the cladding masonry method of magnesia carbon brick in domestic steel works is as follows: after the cladding brick is finished, the pouring material is filled at the place 150-200 mm away from the ladle shell on the top surface of the ladle mouth brick, and the flange ring is auxiliary welded to protect the built cladding brick. However, the ladle mouth material will fall off in the process of use, which will affect the use of the ladle. Each time the ladle is off-line for minor repair or major repair, the ladle mouth needs to be repaired, and the damaged flange ring needs to be re welded, which directly affects the ladle operation, the flange consumption is more, and the use of castable is increased. Through the test and research, the ladle mouth prefabricated parts are designed. After installation and use, the ladle mouth utilization rate can be increased, the ladle edge erosion can be reduced, and the repair work of the ladle shell flange ring can be reduced, and the cost can be saved.

It can be seen from the package that the prefabricated parts have little erosion and no spalling, and the cladding bricks are well protected and there is no looseness of the capping bricks; however, the capping parts filled with castables at the same time are easy to fall off during the use process and need to be repaired at any time, and the cladding bricks are seriously exfoliated. The second furnace service is used for the ladle with prefabricated parts. The bricks are directly laid after the ladle bricks are removed. The ladle mouth flange and prefabricated parts are not needed to be repaired, and they can be directly put into use after baking. However, the ladle without prefabricated parts needs to be welded again and the ladle mouth can be put into use only after masonry.

Three furnace services were used for 210 heats of steelmaking. The oxidation depth of each furnace was about 60mm. The residual thickness after the final removal was 1 / 2 of the design thickness, which met the design requirements. It can be seen that the use of prefabricated parts improves the utilization rate of ladle mouth, which is increased from one time of pouring ladle mouth in each furnace service to one time of installation in 3-4 furnace service, and can be disassembled and replaced at any time in the process. This not only reduces the welding work of flange ring, saves the material and labor cost of the steel plant, but also reduces the use of ladle mouth castable, effectively protects the ladle mouth brick, makes the ladle use stable, can meet the requirements of the steel plant, and has good contracting benefits.

Molding is an important factor to densify the structure of refractory brick: due to the large amount of graphite in the slurry and the small critical particle size of aggregate, high-pressure molding should be adopted, and the operation procedure of first light then heavy and repeated pressure should be strictly followed to avoid forming cracks. Good use of vacuum, exhaust pressure operating procedures. In addition, the surface of the high-pressure molding brick is very smooth, and it is easy to slide when handling and building. Therefore, the formed brick should be dipped or coated with 0.1-2 mm thick thermosetting resin to form a resin film to prevent sliding. This treatment is generally referred to as antiskid treatment.

The moulded brick can only be used after hardening treatment. The epidemic of hardening treatment has a great influence on the performance of refractory brick. It has been proved that the hardening treatment at 200-250 ℃ is more suitable for ensuring the bulk density and reducing the porosity of the brick. When the temperature is higher than 250 ℃ and lower than 200 ℃, the hardening treatment will bring adverse effects. It is necessary to strictly improve and control the air. Generally, when the temperature is 50-60 ℃, due to the softening of the resin, it should be kept warm; when it is 100-110 ℃, because there is a large amount of solvent discharged, it should be kept warm; if the temperature is 200-250 ℃, it should also be kept properly to make the reaction complete.