01. Steelmaking system
The steelmaking system includes equipment such as converter, electric furnace, off-site refining furnace, ladle and tundish. In the electric furnace, dry vibrating material, prefabricated or cast-in-place furnace cover or furnace cover triangle area and other parts have achieved good use effect; in the converter and electric furnace, refractory spray coating is generally used for repair when damaged, and the methods include manual repair, wet, dry or flame spraying and slag splashing furnace protection. In the converter, slag splashing furnace protection technology is generally used, and the furnace life can reach more than 10,000 times; there are many types of off-site refining furnaces, and the insert tube lining of the RH method and DH method degassing device is generally cast as a whole with high-aluminum refractory castables, with a service life of 20 to 80 times. Ladle and tundish are important auxiliary equipment of steelmaking furnaces and thermal equipment that consumes the most refractory materials. In the past, ladles were generally built with fired bricks such as clay refractory bricks, high-aluminum refractory bricks, semi-silica bricks and wax stone bricks, with a service life of 10 to 70 times. When ladle blowing or continuous ingot casting is used, the ladle age drops sharply due to high tapping temperature and long residence time. Therefore, countries attach great importance to the development of ladle lining materials and have made significant progress. A steel plant uses a 200t ladle for converter, and uses aluminum-magnesium castables and self-flowing materials to build linings, with ladle ages of about 95 and 80 times respectively; a steel plant uses a 300t ladle for converter, and uses high-purity aluminum-magnesium castables to build linings. After repair, the ladle age is generally about 260 times, and the unit consumption of refractory materials is less than 1.78kg; many steel plants in the country use new technology aluminum-magnesium refractory castables for ladles not larger than 100t, and their ladle age is about 90 times, and the cost of casting steel is 5.50~7.50 yuan per ton of steel. The lining of the intermediate ladle is made of insulation board or magnesium coating, and the slag weir is made of mullite, aluminum-magnesium and magnesium refractory castables, which can meet the technical requirements of continuous steel casting. The integral spray gun for off-furnace refining is used for ladle slag blowing or ladle powder spraying, etc. The part above the slag line is made of high-aluminum refractory castables, and the part from the slag line to the nozzle is made of low-cement corundum refractory castables, which are vibrated into an integral wrapped lining.
02. Ironmaking system
The ironmaking system includes sintering, coking and blast furnaces and their ancillary equipment. The belt sintering machine ignition furnace is made on-site with refractory plastic and clay combined with refractory castables, or hoisted with phosphoric acid refractory castable prefabricated blocks, and its service life is 3 to 6 years. When a linear ignition device is used, the furnace top is pressed down more, and the working conditions of the furnace chamber become better. Lightweight high-strength refractory castables or refractory fibers and their products can be used as linings, and better results can be obtained; the coke oven roof insulation layer, covering layer and furnace door are poured with refractory castables, and when the furnace head is damaged, it is repaired with spray paint. In addition, dry coke quenching equipment also uses heavy or lightweight refractory castables; blast furnaces are continuous production ironmaking equipment. Small blast furnaces were once built with prefabricated blocks of aluminate cement and high-alumina phosphate refractory castables, but now they are generally built with resin-bonded aluminum-carbon unburned bricks. The water-cooled walls of large blast furnaces are rammed with silicon carbide castables, and the bottom cushion and surrounding brick joints are made of refractory castables and silicon nitride fillers. When the furnace lining is damaged, it is repaired with refractory press materials and refractory spray coatings to extend the service life and make the furnace life reach 10 or even 15 years. The blast furnace taphole is generally blocked with loose Al2O3-SiC-C taphole mud, which can ensure stable tapping and normal operation. The blast furnace taphole was originally rammed with refractory ramming materials, and the unit consumption of ton of iron in the ditch was about 1.1kg. Now it is cast with low-porosity dense refractory materials, and the iron flow rate at one time reaches about 100,000 tons. The cumulative iron flow rate of one generation of ditch age is about 900,000 tons, and the unit consumption of ton of iron of refractory materials is less than 0.38kg. At the same time, self-flowing refractory castables and baking-free refractory castables are also used on the blast furnace tapping hook. The hot blast furnace is a key auxiliary equipment of the iron-making blast furnace. The lining of the hot blast furnace of medium and small blast furnaces is built with prefabricated blocks of refractory castables. The burner of the hot blast furnace can be built with prefabricated blocks of refractory castables or poured on site, and the ball top is poured with castables for working lining. The first layer of lightweight spray coating with a volume density of about 1.3g/cm3 on the furnace shell of a large hot blast furnace is sprayed with a layer of acid-resistant spray coating to form an integral lining. Corundum refractory castables and other materials are used for on-site pouring, which has achieved good use results; torpedo-type iron molten ladle and mixed iron furnace generally use refractory castables partially or completely, and can also be repaired with refractory spray coatings, with good use results.
03. Building materials system
The building materials system includes industrial sectors such as cement, glass and ceramics. The cement kiln lining uses high-alumina phosphate or magnesium and magnesium-chrome unburned bricks with a service life of 6 to 18 months, and amorphous refractory materials are also used in some parts. The rotary kiln of a large cement plant uses 19% to 35% of refractory castables, and its main varieties are low-cement refractory castables, aluminate cement refractory castables, silicon carbide refractory castables and thermal insulation castables; in the glass industry, the tin bath on the float glass production line is made of refractory castables. In addition, when the glass tank kiln is damaged, it is repaired with silicon repair materials. When the new tank kiln is insulated, silicon thermal insulation castables are generally used; kilns in the ceramic industry sometimes use silicon carbide refractory castables and lightweight refractory castables.
04. Steel rolling system
The steel rolling system has many types and large quantities of industrial furnaces, and the operating temperature is generally below 1400℃, all of which are flame furnaces. The kilns in this system can all be lined with amorphous refractory materials, and good economic results have been achieved. The steel rolling heating furnace uses refractory plastic as the lining, which has a long service life. The service life of the furnace lining is generally 4 to 10 years when the clay combined with refractory castable is used as a whole. For the regenerative heating furnace, the micro-expansion refractory castable should be used as the lining. It has been used for more than 2 years and is intact. Forged steel heating furnaces are generally intermittently operated, with large temperature changes and vibrations. Brick lining can be used for 2 to 5 months, and adhesive combined with refractory castables can be used for more than 2 years. It is well known that the operating temperature of the steel rolling heating furnace is <1400℃ and intermittently operated. Domestic and foreign production practices have proved that the lining material should be Al203≤65%, and the compressive strength after drying and 1400℃ burning should be 20~25Mpa and not less than 60Mpa respectively, so as to achieve the purpose of longevity. Because the refractory castable with high aluminum content and high strength has poor thermal shock resistance, it is easy to peel and crack during use, which affects its life.
05. Other industrial systems
In the petrochemical industry, lightweight refractory castables with a volume density of 0.5~1.0g/cm3 are used for tubular heating furnaces. They are constructed by hand-painting or spraying, and have a service life of about 5 years. The use of refractory spray coatings to build linings has also achieved good results. In particular, wear-resistant refractory castables have been used in platinum reforming units, which can eliminate the heat-resistant steel tortoise shell mesh system and increase its service life. The linings of various converters have an operating temperature of 600~1500℃, and generally use aluminate cement refractory castables, low cement refractory castables and corundum castables, etc., with a service life of 3~6 years; in the non-ferrous metallurgical industry, thermal equipment such as lead-zinc closed blast furnaces, flash furnaces, electrolytic cells and rolling heating furnaces use amorphous refractory linings in some parts. Recently, anti-permeability refractory castables have been widely used in aluminum electrolytic cells, achieving satisfactory results; amorphous refractory materials were used earliest and most commonly in the linings of steam boilers. Generally, heavy or light refractory castables made of aluminate cement are used, with a service life of about 10 years. Fluidized bed power generation boilers use high-aluminum, corundum and SiC refractory castables and refractory plastics, which have high strength and good wear resistance, meeting the design and use requirements. In addition, amorphous refractory materials are also used in the machinery, refractory and waste incineration industries, and good results have been achieved.