The converter plays the functions of decarburization, dephosphorization, desulfurization, alloying, heating, and removal of inclusions in steelmaking. The converter does not need external heat during smelting, relying on the heat release of the oxidation reaction in molten steel. In the converter, the furnace lining, the tap hole, the ventilation brick, etc. are all made of refractory materials. Graphite is widely used in magnesia carbon brick because of its poor wettability with steel slag. Rongsheng kiln refractory manufacturers provide high-quality refractory materials for converters, including mag carbon bricks, low-carbon magnesite carbon bricks, hot repair materials, gunning materials, etc.
Magnesia Carbon Brick for Steelmaking Converter Furnace
The graphite content in traditional magnesia-carbon bricks is too high, on the one hand, it will increase the carbon content of molten steel, and on the other hand, it will cause a large amount of heat loss. Simply reducing the carbon content of magnesite carbon bricks will lead to problems of poor oxidation resistance, thermal shock resistance, and slag resistance. In response to the above problems, researchers improved the performance of low-carbon magnesia-carbon bricks through three aspects: binder modification, high-efficiency antioxidant application, and raw material optimization.
-
binder modification
A catalyst is introduced into the carbonaceous binder to generate carbon nanostructures in situ to improve the oxidation resistance, thermal shock resistance, and slag resistance of low-carbon magnesia-carbon bricks. A commonly used binder is a phenolic resin. However, it will become isotropic glassy carbon with high brittleness after carbonization, and release many gaseous products during the transformation of organic groups. This will affect the thermal shock resistance and high-temperature mechanical properties of low-carbon mag carbon bricks.
-
The application of high-efficiency antioxidant
Oxidation is the main factor affecting the service life of low-carbon magnesia-carbon refractories. Adding antioxidants is a common and effective method to inhibit carbon oxidation. The role of antioxidants is to preferentially oxidize carbon or generate ceramic phases to fill pores and prevent oxygen media from entering refractory materials. Antioxidants in low-carbon magnesia-carbon refractories are metal powders, carbides, and borides.
-
Raw material optimization
The main raw materials of low-carbon magnesia-carbon refractories include magnesia and graphite. The contact area between graphite and magnesia is greatly reduced after the graphite content is reduced. It leads to uneven dispersion of graphite in the matrix, which reduces the thermal shock resistance and slag resistance of the material. There are studies to control the porosity in low-density materials through measures such as particle size distribution and carbon source. The particle gradation in low-carbon mag carbon bricks was calculated according to the Andreassen formula of the continuous closest packing theory of particles. The study found that when the critical particle size is 3 mm, appropriately increasing the proportion of coarse particles in low-carbon magnesia-carbon bricks can increase the bonding area between a single coarse particle and the matrix, increase the fracture surface energy, and improve thermal shock resistance.
Researchers from a Japanese refractory company found that the better the high-temperature mechanical properties of magnesia-carbon bricks, the stronger the damage resistance. Developed and applied to different parts of the converter through two methods of strengthening the matrix of mag carbon bricks or carbon bonding. Ultrafine graphite and graphite with different particle sizes can be well-filled in the voids of low-carbon magnesia-carbon materials to densify the material matrix. Introduce carbon-containing micro powder into the low-carbon magnesite carbon bricks matrix and use amorphous graphite + flake graphite to reduce the porosity of the sample and improve the mechanical properties. The oxidation resistance of amorphous graphite is better than that of flake graphite, and the combination of the two can improve the oxidation resistance of low-carbon magnesia carbon brick. This low-carbon magnesia-carbon brick is applied to the field, and the average erosion rate of the test package is 1.08mm/furnace lower than that of the normal package, which has a good application prospect.
The Converter Furnace Lining Maintenance
Magnesia-carbon repair materials are used for the repair of the large surface of the converter, which will generate a lot of black smoke and take a long time to repair, which is not conducive to the site environment and the benefit of the steel plant. Based on this problem, some researchers used mid-grade magnesia and fused magnesia as the main raw materials, introduced sintering aid aluminum powder, and modified asphalt binder, and developed an environmentally friendly rapid sintering large surface repair material. Adding a small amount of liquid wetting agent and flow aid when using, it has good environmental protection, short sintering time, and an average life span exceeding 34 furnaces.
The converter trunnions and furnace bottom are subject to mechanical stress and slag erosion, requiring frequent gunning of these two parts. In order to improve the shortcomings of the existing magnesia-carbon repair materials that are not resistant to erosion and erosion, a gunning material with magnesia as raw material and carbon and pitch as binders has been developed. After field application, the service life of the original gunning material has been increased by 30%.
Rongsheng Refractory Bricks Manufacturer
Rongsheng refractory brick manufacturer is a powerful refractory brick production and sales manufacturer. We provide high-quality refractory lining products and insulation material products for various thermal kilns. Including refractory bricks like high alumina bricks, magnesia bricks, carbon bricks, chrome bricks, corundum bricks, etc. If you need to buy mag carbon bricks for converters, low carbon magnesia carbon bricks, converter hot repair materials, gunning materials, etc. Please contact us. Neither our products nor customer service will disappoint you.
Leave Your Requirements on RS Kiln Refractory Bricks And Castable Materials! We Will Reply You In 12 Hours!: