uses the fourth generation of Theron carbon-nitrogen high-strength composite material to pour the blast furnace cylinder as a whole, which fundamentally solves the complex construction and air blowout problems of traditional masonry brick lining. It is widely used in blast furnace furnace cylinder maintenance and newly built blast furnace furnace cylinder design, greatly improving construction efficiency and reducing repair costs. At present, in the maintenance of some blast furnaces in China, the furnace cylinder pouring has extended to the furnace belly, furnace waist, and other parts.
1 Advantages of the overall pouring technology of the furnace cylinder
According to the different working conditions and environments of each part of the blast furnace, the blast furnace lining material will be dissolved to varying degrees. Generally, the blast furnace lining is quickly repaired by thermal repair; while the furnace cylinder lining is repaired by short-term shutdown overall pouring. The overall casting of the furnace cylinder is a typical application of amorphous castable material. Its application environment is even more complex than the blast furnace body. Therefore, for materials and processes, factors such as operating ambient temperature, mechanical erosion, and chemical erosion should be considered. On the one hand, it depends on slag hanging to protect the working lining, and on the other hand, the material needs to have the best performance.
There are usually two solutions for the maintenance of the hearth: combined brick masonry and integrated hearth pouring. The former is usually used for the design of a new blast furnace furnace cylinder, while the latter is often used for the repair of the furnace cylinder during the middle repair process. In recent years, newly built blast furnaces have also generally used the overall casting method to design the furnace cylinder lining, which originated from the following aspects:
(1) Combined brick masonry, with a long prefabrication cycle and required prefabrication, making it difficult to process;
(2) Combined bricks with air outlets, the brick design is relatively complex, the masonry is difficult, and it is prone to masonry deviations, causing the furnace to be blown off later;
(3) Combined brick materials cannot form an effective slag-iron sticky layer, and the service life of the upper brick lining is relatively low.
West China furnace cylinder is poured into (patent number: ZL201610353176.4), using West China's fourth generation Theron carbon-nitrogen high-strength composite material, the hearth lining is repaired through mold casting. The overall construction period is ≤7 days. Its advantage is:
(1) Eliminates the two major ceramic cup The gap (the gap between ceramic tiles, the large gap between ceramic cups and carbon bricks) prevents water vapor, alkali metal and other harmful elements from eroding carbon bricks, and effectively protecting carbon bricks;
(2) can leave the high-temperature and sharp temperature drop zone in the castable, reduce the temperature inside the carbon bricks to below 800℃, reduce the thermal stress in the carbon bricks, reduce the occurrence of carbon brick ring cracks and embrittlement layers, and maintain the thermal conductivity of carbon bricks. In the application of long-lived blast furnaces, as long as the thermal conductivity of the blast furnace carbon bricks continues to exist and the thermal conductivity is not lost due to annular cracking and embrittlement, the longevity of the blast furnace is guaranteed;
(3) The furnace cylinder castable we use has good slag hanging properties, and a stagnant layer can be formed on the hot surface, which can further protect the furnace cylinder carbon bricks; the semi-conductive castable material poured by the furnace cylinder is closely bonded to the carbon bricks, and the heat can be transmitted to the cooling wall through the highly thermally conductive carbon bricks, which can reduce the temperature of the castable layer to below 1150℃, thereby forming an iron-carbon solidification layer to protect the castable material, and then the castable material protects the composite slag peel mechanism of the carbon bricks.
2 4 The fourth generation of Theron carbon-nitrogen high-strength composite castable
(1) Use the ductility of metal (Si/Al) to achieve plastic molding, use the nitriding and reducing atmosphere in the blast furnace to synthesize the high-temperature reinforced phase (Si3N4/SiAlON) in situ, forming a perfect inlay structure with the non-oxide substrate, and at the same time realize:
◆Excellent chemical corrosion resistance
◆It has self-healing function during use
◆Good thermal shock resistance
(2) Based on the metal-non-oxide composite system, it is based on the non-oxide surface modification and uses the sol-gel molding process to achieve:
◆Good fluidity
◆Fast drying performance
◆Overall stability after drying
West Hua Technology's fourth generation Theron carbon and nitrogen high-strength composite castable, solving the defects of traditional binding agent-bound castable.It has excellent wear resistance, good chemical stability, higher flexural strength, better thermal conductivity, and high-quality slag-making ability.
3 overall pouring process and effect of the furnace cylinder
1. The carbon bricks that are partially eroded in the side wall of the furnace cylinder are subjected to mold-casting repair;
2. The furnace bottom is leveled, and a springboard is set up to pour the furnace bottom coaster;
3. The furnace side wall is built to build a template and pump the pouring;
4. The iron mouth area is thickened and poured with a 1500mm high template;
5. The mold is released after 8 hours of pouring and maintenance;
6. The furnace is oven-dry according to the provided oven plan.
4 4 4 Furnace cylinder pouring air outlet expansion problem
Overall pouring technology of air outlet belt was initially applied to rapid maintenance of blast furnaces. After the furnace is opened, there is a problem of blow-off or the problem of "removing the middle sleeve" is not properly handled. This is the reason why the material expansion is not properly handled during the pouring process. These two situations are derived from:
(1) There is no expansion joint between the middle sleeve and the cast material, and the castable body will have a problem of "wind cover" expansion. The wind sleeve is raised, causing difficulty in "retreating the cover" process, and air bleed will occur after installation;
(2) An expansion joint is set between the middle sleeve and the castable material. If the expansion joint is not set up, there will be a problem of air bleeding in the air outlet after opening the furnace. This is the most common problem.
For the above problems, the common solution is: use asbestos rope to wrap the air outlet middle sleeve, or use ceramic fiber blanket to wrap the air outlet middle sleeve, etc. to offset the expansion of the cast body, and then use the method of plugging material at the top of the middle sleeve + cold-side grouting to solve the problem of air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet air outlet As mentioned above, the material itself has metal phase absorption and expansion, so the air vent tape pouring technology is relatively mature, and various problems caused by material expansion have been completely solved.
5 Application Expansion
The application of the overall pouring technology of West China furnace cylinder has been widely used in the maintenance of major, medium and small blast furnaces in recent years. The maintenance cycle is short, and this short, flat and fast maintenance method is efficient and long-lived. The following are two types of expansion applications:
1, West China cooling wall hot surface casting technology (patent number: ZL201811449733.8)
West China's unique innovative cooling wall hot surface casting technology has two construction methods: one is poured on the outer mold of the furnace, and the other is to build a frame and support mold casting in the furnace. Based on the actual situation on site, it is decided to adopt the outer mold casting method.
cooling wall hot surface casting technology, which gives full play to the advantages of metal and non-metallic materials, has excellent performance, is easy to hang slag, and is easy to install and use on site. It can form slag well on the hot surface of the cooling wall, improves the protection performance of cooling wall , fundamentally solves the problem of water leakage and damage in the cooling system, greatly improves the service life of the cooling wall, and achieves efficient, safe and stable operation of the blast furnace.
2, West China integrated full furnace pouring technology (patent number: ZL2020109906820) is a new longevity blast furnace integrated pouring technology of . According to the different erosion mechanisms of each part of the blast furnace, a variety of carbon and nitrogen composite casting materials are used. The overall casting molding is seamlessly connected, prevents iron from corrosion resistance, and the furnace cylinder casting layer comes into contact with the annular carbon bricks, which has very high thermal conductivity. It is one of the symbols of the development level of long-lasting ironmaking technology for blast furnaces, and it is the fastest and most effective method for intelligent lining, energy-saving and consumption-saving lining.
6 Conclusion
The overall pouring technology of Huaxi Technology has been widely used in blast furnace maintenance and new blast furnace design.This article briefly introduces the process and pros and cons, and briefly describes it as the following conclusions:
(1) The furnace cylinder is poured in an integral manner, which fundamentally solves the complex construction and gaps of traditional masonry brick linings;
(2) West China's fourth-generation Theron carbon-nitrogen high-strength composite material is more suitable for the furnace cylinder operating environment and longer life after continuous research and development and improvement;
(3) The newly built blast furnace lining design, after comprehensive comparison, more and more overall pouring methods are used to make lining;
(4) The application of integrated full furnace pouring in blast furnace can effectively improve the operating life of blast furnace lining, which is conducive to the efficient and safe operation of blast furnace.
