In view of the technical problems existing in the lining refractory materials of the ladle, the management status of smelting production and operation, and the actual needs of Baosteel’s steelmaking production line for multi-grade smelting production, it is very necessary to develop a new generation of lining refractory materials that can meet the requirements of safety and longevity of ladle lining refractory materials, anti-slag adhesion, and no impact on the cleanliness of molten steel. The specific research and development directions are as follows:
Develop oxide-non-oxide composite refractory working layer or micro-carbon refractory working layer
1.Development prospects of oxide-non-oxide composite refractories
Non-oxide high-temperature materials have good resistance to slag wettability and good refractory properties. The solid solution formed by non-oxides and oxides, such as Sialon materials, has the refractory properties of high-temperature oxide materials and the resistance to slag and molten steel wettability of non-oxide materials. According to the material composite process, oxide-non-oxide composite refractory materials are made. Generally speaking, new materials with both characteristics can be obtained. According to the working conditions of ladle smelting, it is possible to reasonably select oxides, non-oxides and their composite processes to develop ladle lining refractory materials with excellent slag penetration resistance, uniform melting loss on the working surface and long service life. Under the current raw material industry conditions, silicon nitride and silicon carbide oxide composite materials are more feasible as lining refractory materials in terms of performance and cost. Preliminary tests show that the slag resistance and melting loss resistance of this type of material are significantly improved compared with existing lining materials.
2.The development prospects of micro-carbon refractory materials
Micro-carbon refractory is the latest development in carbon composite refractory technology. The use of nano-carbon technology can obtain the slag penetration resistance and excellent refractory performance required by the lining material. Compared with carbon composite refractory with high carbon content, the thermal conductivity of carbon-containing refractory is significantly reduced at the micro-carbon content level, and the carbon increase effect on molten steel is very slight, which generally does not affect the smelting of ultra-low carbon steel. Therefore, the development of micro-carbon refractory technology is also a feasible solution to solve the current slag sticking in the working layer of the ladle.
3.Key technologies for the development of oxide-non-oxide composite lined refractory or micro-carbon lined refractory
(1) Reasonable antioxidant selection and matrix densification measures can make the composite material obtain better antioxidant effect. Assisted by the existing MgO-C brick slag line surface antioxidant coating measures, the antioxidant problem in the use of new lining materials can be solved.
(2) The melting loss rate of the material is reduced by optimizing the addition state and compounding amount of non-oxide or micro-carbon materials to prevent the new lining material system from affecting the cleanliness of molten steel.
(3) The uniform dispersion of nano or submicron carbon in the material structure of micro-carbon refractory is another key to the material technology. Conventional dispersion technology is difficult to achieve the dispersion requirements. This project will explore the co-preparation process of high-efficiency dispersant and fine powder components to achieve the technical goals.
As a new generation of ladle lining refractory, due to the lack of historical accumulation of technology, the new material system needs to obtain the necessary basic properties of ladle lining materials, such as anti-corrosion and spalling performance, anti-corrosion, high temperature volume stability, thermal shock stability, and reasonable strength at high temperature and room temperature. It also needs to form a complete new generation of lining refractory technology through systematic research on material composition, preparation process, material properties and use damage process.
Development of high-strength, low-thermal-conductivity, high-fire-resistant, permanent layer technology
Develop low-density castable technology, change the current dense castable technology scheme used in the overall permanent layer castable, the bottleneck restricting the refractory damage process is the matrix fine powder area in the refractory organization, by improving the refractory performance of the matrix, reducing the density of the particle components, so that the density, thermal conductivity and lining weight of the castable are reduced, but the safety and service life of the lining can still be well guaranteed, forming a semi-lightweight overall permanent layer that takes into account both safety and thermal insulation performance.
Through the advancement of the combination technology of lining insulation prefabricated panels and micropore formation technology, the thermal insulation performance of the current lining insulation layer is further improved, and the use of nano-micropore series insulation materials with better thermal insulation effect is explored, so that the thermal insulation performance of the lining and the thermal state of the ladle are significantly improved.