1) Characteristics of castable prefabricated blocks
The castable prefabricated block only needs to be heat treated at a lower temperature, it is a low carbon and green refractory material, and it is a unique technology in the refractory lining technology. It can improve the performance of the refractory lining, reduce the consumption of refractory materials, and has stable quality and reliable performance. We know that the purpose of adding steel fibers to the castable is to improve the mechanical properties of the castable, inhibit the occurrence of cracks or limit the propagation of cracks when they are formed. The figure below is a diagram of the steel fiber castable. The steel fiber castable prefabricated block is made by a special process. According to the process position and needs, it is made into a certain shape, and after demolding, heat treatment is carried out according to its working conditions.
2) Application of unshaped refractories in blast furnaces
Blast furnace is an important equipment for iron making. Small blast furnaces used to be hoisted and built with high alumina cement and high alumina phosphate refractory castable prefabricated blocks. Now, resin-bonded aluminum-carbon unburned bricks are commonly used for masonry. The water wall of large blast furnace is rammed with SiC castable, and the bottom cushion and surrounding brick joints are made of refractory castable and silicon nitride filler. A development trend of refractory materials for furnace walls is the use of castables. A high-density castable of Al₂O₃50% and SiO₂ 45% is used in the No. 2 blast furnace of the Fukuyama Plant of Japan Steel Pipe Company. After 6 years of use, very little peeling was found.
At present, the unshaped refractories used for blast furnace tapping trenches at home and abroad are mainly Al₂-O₃-SiC-C (ASC for short), in addition to mullite-SiC-C, Al₂O₃-C, magnesium-aluminum spinel type of stone. Corundum-SiC castables are mainly used in my country. Most of the blast furnace taps in Japan now use ASC castables and repair gunning materials, and some small blast furnace taps use bauxite or synthetic mullite-SiC-C ramming materials. ASC ramming material is generally used in the blast furnace tap ditch in Germany and France. France has developed self-flowing castables, which have improved the working life of the working lining of the main tap ditch.
3) Application of unshaped refractory material on ladle
The increase of the tapping temperature and the prolongation of the residence time of the molten steel in the ladle have caused great changes in the refractory materials for the ladle. The ladle used to be dominated by shaped refractories, but is now replaced by unshaped refractories. The unshaped ladle can not only save labor, but also realize the automatic construction and drying of the factory, and improve the overall economy. When the side wall of the ladle is indeterminate, the maintenance operation time can be saved by 40%, and when the lining of the ladle is all indeterminate, the labor-saving effect is 70%. Because Al₂O₃-spinel castable has the advantages of good corrosion resistance, small structural spalling, long service life and improved steel quality, it has become the main role of the current ladle refractory material. However, its use is limited by the temperature and the residence time of molten steel. The Al₂O₃-MgO castable developed by Kawasa-ki Company in Japan has improved material strength and slag penetration resistance, and its life is 20 times higher than that of Al₂O₃-spinel castable. %. At present, magnesia refractory castables and aluminum-magnesium carbon refractory castables have been tried on ladle, and initial results have been achieved.
4) Application of amorphous refractories in non-ferrous metallurgy
Aluminium smelting reverberatory furnace is a major consumer of refractory materials in aluminium plants. The refractory materials for the hearth have changed from brickwork to a monolithic structure. The refractory materials in contact with the metal on the hot side of the hearth are usually acid-bonded plastic, phosphate-bonded bricks and low-cement castables, and the hot side of the lower side wall is refractory. The material composition is usually the same as that of the hearth, and the thermal insulation material can be made of lightweight thermal insulation castables, thermal insulation clay bricks or ceramic fibers, etc.; the furnace top materials are usually high-quality refractory materials such as ramming materials and sintering materials; the furnace door is usually made of dense Castables or lightweight castables, or a mixture of the two can also be used for casting.
In electrolytic aluminum smelting, amorphous refractory materials are mainly used in aluminum buckets. The refractory material for the aluminum bucket is required to be able to withstand the erosion of aluminum water, to withstand the effect of rapid cooling and rapid heating, and to have good thermal insulation performance. The non-working lining of the aluminum ladle generally adopts lightweight castables or lightweight high-alumina bricks. If the molten aluminum in the aluminum ladle is to be placed for a long time, a heat-insulating castable is usually used to prevent the molten aluminum from solidifying during transportation. Now in order to reduce the self-weight of the tank and strengthen the thermal insulation effect, alumina hollow ball refractory castable is used for the non-working lining. The working lining is generally made of high-alumina bricks with low SiO₂, and some tanks are now made of corundum refractory casting. In the copper smelting industry, basic refractories are widely used in roughing furnaces because CuO is very aggressive as a component of slag. For example, all parts of reverberatory furnace, converter, flash furnace and rotary anode furnace use basic magnesia-chrome brick or basic ramming material based on MgO, especially when repairing the furnace. In the refining part, aluminum silicate refractories such as castables, plastics, spray coatings and high-alumina bricks can be used due to the decrease in the amount of slag and the temperature.
