Abstract: This paper discusses the comprehensive maintenance technology of carbon-free steel ladle lining from three aspects of comprehensive masonry, partial repair or lining and slag line maintenance. By adding different carbon sources into the carbon-free ladle corundum bricks to conduct water-cooled thermal shock tests and combining the field use, it is concluded that the contact layer between carbon-containing bricks and carbon-free bricks, carbon elements diffuse into the carbon-free bricks, and promote carbon-free For the spalling of corundum bricks, use special fireclay to wet the contact layer during construction to slow down the diffusion of carbon elements, and strengthen the weak link by lengthening the wall-wrapping working layer at this part; at the same time, lengthen the lower slag line and use the special tire film for the lower slag line to form 50 ～80 mm thick corundum castables can reduce the influence of the lower slag line due to erosion and erosion; lengthen the lining bricks in the impact zone of the cladding wall to improve the impact resistance. On the basis of the above comprehensive masonry, the carbon-free ladle lining is combined with local repairs, the overall use of smears for lining or wet spraying for lining maintenance technology, to improve the comprehensive life and promote the lining to maintain synchronous corrosion.
Refractory materials for iron and steel smelting represented by ladle lining have an important impact on the quality of molten steel. With the structural transformation of iron and steel enterprises, the refining ratio gradually increases. , and the rapid drop in temperature of molten steel and high temperature of the ladle shell caused by its high thermal conductivity, there is an urgent need for high-quality carbon-free ladle lining refractory materials. According to different molding and masonry methods, carbon-free ladle lining materials are usually divided into machine-pressed bricks, pouring prefabricated blocks and integral castables. Integral castables have certain advantages in terms of service life, but ordinary integral castables have poor burst resistance, so there are strict requirements on the baking rate. The castables are prefabricated into prefabricated blocks of shaped bricks and constructed by masonry. . Compared with prefabricated blocks, the machine-pressed bricks prepared by the unfired process have the characteristics of high production efficiency, low apparent porosity, simple maintenance process, stable and controllable product quality, and relatively low production costs, which are conducive to the competitive development of the metallurgical industry chain [1 ,2,3]. Regardless of whether the inner lining is made of machine-pressed bricks, poured prefabricated blocks or integral castables, the erosion of the inner lining is very uneven due to the flow (stirring) of molten steel and slag during use, and the weak links of the ladle are damaged, resulting in overhaul and demolition. The package and package age have dropped significantly, which not only affects the pace of steelmaking production, but also increases the consumption of refractory materials, resulting in a large waste of resources. From the point of view of sustainable development, the inner lining should be kept corroded synchronously, so it is proposed to carry out comprehensive maintenance on the inner lining to improve the service life. In the article, it is discussed and explained from three aspects of comprehensive masonry, partial repair or lining and slag line maintenance.
1 Comprehensive masonry
1.1 Masonry
The slag line on the ladle working layer for smelting low-carbon high-quality steel adopts magnesia-carbon bricks, and the cladding wall adopts the masonry method of carbon-free corundum bricks. During use, it was found that the 2-3 layers of carbon-free corundum bricks at the part where the wall-clad working layer was in contact with the upper slag line eroded abnormally quickly (as shown in Figure 1). In the process, the spalling of carbon-free corundum bricks was accelerated, and it was verified by water-cooled thermal shock tests in the laboratory (Table 1 and Figure 2). In view of the abnormal fast erosion of this part, the length of the wall-wrapped brick at this part is lengthened, which is called the wall-wrapped strengthening layer, and when the contact layer between the carbon-free corundum brick and the upper slag line is built, special fire clay is used for masonry between layers to block as much as possible. Diffusion of carbon.
Converter tapping sometimes impacts the cladding slag surface, and this part is built with elongated carbon-free cladding bricks, which is called cladding impact area strengthening, and is strengthened.
Adding a small amount of carbon source to the carbon-free corundum machine-pressed bricks will make the thermal shock performance of the sample worse. Combined with the spalling of the carbon-free corundum cladding at the part where the cladding working layer contacts the upper slag line during field use, it can be concluded that the carbon-containing bricks and Without carbon brick contact, the diffusion of carbon elements promotes the peeling of corundum bricks.
