refractory magnesia carbon brick in iron and steel metallurgy industry
Application of refractory magnesia carbon brick in iron and steel metallurgy industry
Refractory magnesia-carbon bricks are very suitable for the requirements of steel smelting because of their superior high temperature resistance, slag erosion resistance, and good thermal shock stability. Using carbon materials that are difficult to be wetted by slag, molten steel, and the high refractory properties of magnesia, high slag resistance and solubility, and low high-temperature creep, magnesia-carbon bricks are used in severely corroded slag lines and products. Steel mouth and other parts. So far, due to the massive use of magnesia-carbon bricks in the steelmaking process and the improvement of the steel smelting process, huge economic benefits have been created.
1. The use of refractory magnesia carbon brick on the converter lining
Because the working conditions of each part of the converter lining are different, the effect of the use of refractory magnesia-carbon bricks is also different. The furnace mouth part of the furnace lining is constantly impacted by cold and hot molten steel, so the refractory materials used in the furnace mouth must be resistant to the erosion of high temperature slag and high temperature exhaust gas, and it is not easy to hang steel and is easy to clean in time. The furnace cap is not only subject to severe slag corrosion, but also subject to rapid cold and hot temperature changes, as well as the combined effects of high-temperature air flow due to carbon oxidation and dust and high-temperature exhaust gas. Magnesia carbon brick. The charging side requires magnesia-carbon bricks to have high resistance to slag erosion, but also to have high high temperature strength and good peeling resistance. Therefore, high-strength magnesia-carbon bricks with metal antioxidants are usually used. Research shows , The high-temperature strength of the magnesia-carbon bricks with metal aluminum at lower temperatures is lower than that of the samples with metal aluminum and metal silicon, but at high temperatures, its high-temperature strength increases instead. The slag line is the junction of the three-phase refractory material, high temperature slag, and furnace gas. It is the most severely corroded part. Therefore, it is necessary to build magnesia carbon bricks with excellent slag corrosion resistance. The slag line needs to have a higher carbon content. Magnesia carbon bricks.
2. The use of refractory magnesia carbon brick on electric furnaces
At present, the walls of electric furnaces are almost entirely built with magnesia-carbon bricks. Therefore, the service life of magnesia-carbon bricks determines the service life of electric furnaces. The main factors that determine the quality of magnesia-carbon bricks for electric furnaces include the purity of magnesia source, impurity types, and periclase. The state of grain bonding and grain size; the purity, degree of crystallinity and scale size of the flake graphite as the source of carbon introduction; thermosetting phenolic resin is usually used as the binder, and the main influencing factors are the amount of addition and the amount of residual carbon. It has now been proved that adding antioxidants to magnesia carbon bricks can change and improve its matrix structure, but when used under normal operating conditions of electric furnaces, antioxidants are not the necessary raw materials for magnesia carbon bricks, but only arcs used for high FeOn slag Furnace, such as the use of direct reduced iron or irregularly oxidized parts and hot spots of electric furnaces, adding various metal antioxidants can become an important part of magnesia carbon bricks.
The corrosion behavior of the magnesia-carbon bricks used at the slag line is manifested by the formation of an obvious reaction dense layer and a decarburized loose layer. The dense reaction zone also becomes the slag invasion zone, which is the erosion area where the high temperature liquid phase molten slag penetrates into the brick body after the decarburization of the magnesia-carbon bricks forms a large number of pores. In this region, FeOn in the slag is reduced to metallic iron, and even the desolvent phase and intergranular Fe2O3 that are dissolved in MgO are also reduced to metallic iron. The depth of slag penetration into the brick is mainly determined by the thickness of the decarburized loose layer, which usually ends at the place where graphite remains. Under normal circumstances, the decarburized layer of magnesia carbon bricks is relatively thin due to the presence of graphite.
There are two methods for the tapping of the electric furnace: the tapping trough tilting tapping and the bottom tapping. When the tapping channel is used for tilting steel, magnesia-carbon bricks are basically not used, but Al2O3 or ZrO2 are selected, and non-oxygens such as C, SiC and Si3N4 are added. When the bottom of the furnace is used for tapping, the tapping opening is composed of external sleeve bricks and in