The steel industry is a major consumer of refractory materials. According to statistics, the annual consumption of refractory materials in iron and steel enterprises is about 10 million tons, and the refractory materials after use are more than 5 million tons. This does not lead to waste of resources, and at the same time brings environmental pollution. If the used refractories are recycled, not only high-quality unshaped refractories can be produced, but also high-quality shaped products and other materials can be regenerated. This does not save the country's mineral resources and energy, but also reduces environmental pollution and greatly reduces the cost of refractory materials and steelmaking costs. Electric furnace magnesia carbon brick
At present, the methods of repairing and maintaining converter lining mainly include: splashing slag to protect the furnace, dry spraying, wet gunning, pouring and sintering, and magnesia carbon bricks. The use of slag splashing to protect the furnace will cause the temperature of the molten pool to drop faster, and the high viscosity slag will cause the bottom of the furnace to rise, which will affect the smelting effect. After the slag splashing, the oxygen in the molten steel will rise and the quality of the molten steel will deteriorate. The disadvantages of wet gunning include: it will make the wall of the red-hot carbonization chamber subject to the impact of rapid cooling, damage the surface structure of the silica brick, and shorten the life of the furnace; it will cause the repair material to have more water content and increase the pores of the mud. , And the parts in contact with the furnace wall will be violently vaporized, making the mud texture loose, reducing the strength of the repair layer, and being easy to wear and fall off; it will make the adhesion between the repair material at room temperature and the red hot masonry weak , Hanging time is shorter. Dry gunning is the use of compressed air to inject refractory powder into a closed carbonization chamber to seal small gaps in the furnace body. The method is simple to operate, does not require an external heating source, and does not damage the original masonry, but it is suitable for the repair of the coke oven in good condition and small cracks on the wall of the carbonization chamber. It can also be used to further seal the furnace body after semi-dry gunning or welding repair. Dry gunning technology is currently applied in some European countries.
Converter magnesia carbon brick
Domestic large and medium-sized converters generally use the method of filling up the charge to repair the large surface of the converter. There are two main types of supplementary charge, one is non-aqueous series, and the other is water system. Non-aqueous series include tar binder, resin binder, composite binder, etc. The binder of the tar binder contains a variety of polymer hydrocarbons, which are solid at room temperature, softened and melted by heating, and the viscosity decreases with the increase of temperature, resulting in good fluidity, and then the low molecular components volatilize and decompose and polymerize After the reaction, the viscosity gradually increases, forming a carbon-based precursor at a temperature above 600°C, and finally carbonizing. The whole process is slow, takes about 50 minutes, and is accompanied by smoke. At present, the tar binder has been used, which has a long sintering time and requires manual supplementation. The labor intensity is high, and the smoke is serious during sintering, resulting in a poor working environment.
The water system is mainly composed of a water-soluble binder combined with a supplementary furnace material. The sintering mechanism of the water-bonded large-surface repairing furnace charge is that the binder is dissolved in water before the furnace repairing, and stirred evenly with the material. After being poured into the converter, the boiling point of water molecules is low, so it begins to volatilize during the spreading process. The time is very short, about 30 minutes. This method requires additional equipment.
