Ladle is a very important equipment in the steelmaking process. In particular, the quality requirements of steel in modern industry are getting higher and higher, and the demand for pure steel such as low carbon and ultra low carbon is increasing. However, converter steelmaking often cannot meet these requirements. This requires refining outside the furnace to reduce the carbon content and other impurities in the molten steel. The fused magnesia bricks are therefore more and more demanding on the ladle; while the conventional ladle refractories can not meet the requirements or have a very low life. There is no cost competitive advantage. Therefore, the development of efficient and long-life ladle refractories is an inevitable trend of development.
The main factor affecting the service life of the ladle is the damage of the refractory. The reasons include chemical cracking and spalling and cracking caused by thermo-mechanical stress. In addition, the material and its size, masonry structure, expansion joint size, refining conditions, etc. An important factor. At present, the main reasons for the development of China's ladle refractories are the low age of ladle and the problem of wall scum. At present, the working lining of the wall mainly uses magnesia carbon brick, aluminum magnesia carbon brick, magnesium aluminum spinel monolithic castable or precast block, the slag line uses low carbon magnesia carbon brick or low carbon aluminum magnesia carbon brick, and the bottom uses magnesia carbon brick. Or high alumina castables, etc., the life of the ladle is generally around 100 furnaces, and very few steel mills are in the 150~180 furnace. Compared with the same industry level in Japan, the life of ladle is about 250 times.
Ladle slag is also a common problem in China's steel plants. The main influencing factors are ladle slag composition and refractory material. In addition, ladle slag is also aggravated by steelmaking processes and operational factors. Measures to prevent ladle slag can be: 1) increase the hot turnover rate of the ladle and reduce the number of ladle turnover; 2) strengthen the maintenance operation of the ladle, timely clean the ladle along the slagging, and prevent the ladle slag from falling along the mouth Insufficient, repair the obvious melting and peeling parts of the wall in time to avoid the infiltration of slag and molten steel to aggravate the slag; 3) pour the slag as soon as possible after the pouring of the steel, strengthen the production organization of the driving after the furnace, reduce the ladle pouring After the time of turning over the can, avoid the occurrence of ladle slag; 4) increase the operation level of the tapping slag of the converter, reduce the conversion of the converter slag into the ladle, add lime after the furnace and refining, and fully melt the ladle slag; 5) control use The number of ladle in the steel, the waiting time of the ladle is reduced; the ladle is heated by the steel; the ladle is used in use; the permanent layer of the ladle is insulated; the cladding is made of low thermal conductivity; 6) the refractory is used to improve the quality of the masonry. The size of the brick joint reduces the thermal stress of the lining, improves the thermal shock resistance and reduces cracking; 7) Adopts an effective ladle covering agent: improves the spreadability of the ladle covering agent, improves its thermal insulation performance, and reduces the coverage. Agents SiO2 content, reduce its viscosity, to reduce ladle slag viscosity.
To solve these problems, only the narrow concept of refractory steel cost control can not be solved, and it is necessary for refractory suppliers and steel companies to jointly explore solutions to achieve cost from the general cost control of refractory tons of steel.
The practical application shows that reducing the consumption of refractory steel per ton has far-reaching significance for the production of steel-making clean steel, the reduction of tapping temperature and energy saving, and sometimes it is indispensable. For example, the production of clean steel is the dominant concept of modern steelmaking. It usually means that the content of harmful components (S, P, O, H, N) in steel is very small, and the number of non-metallic inclusions is not only small but also small. High-quality steel with controlled shape and precise and uniform distribution of alloying elements. If the refractory material has a high single consumption, there are many refractory materials entering the molten steel, generally entering in the form of melt loss and peeling, and the melt loss is often increased [C], increased [O], and produces less non-metallic inclusions, etc. Produces large non-metallic inclusions. Smaller non-metallic inclusions (≤50ppm) are difficult to remove through existing smelting processes, so low-cost refractories can meet the production of clean steel. At the same time, the low consumption of ladle refractory material indicates that the thermal turnover rate of the ladle is high, the cold-out steel is less, and the average tapping temperature of the converter is lowered. This means that the consumption of oxygen, alloys, etc. is reduced. Usually, the tapping temperature is lowered by 1 ° C, the cost per ton of steel is reduced by 1 yuan, and the low tapping temperature is also advantageous for the quality of the cast slab.
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