Refractory materials actually have different applications in various industries! However, their most common applications are in the following five areas.

(I) Steelmaking system

The steelmaking system includes equipment such as converters, electric furnaces, off-site refining furnaces, ladles and tundishes. In electric furnaces, dry vibrating materials, prefabricated or cast-in-place furnace covers or furnace cover triangles and other parts have achieved good results; In converters and electric furnaces, refractory spray coatings are generally used for repair when damaged. The methods include manual repair, wet, dry or flame spraying and slag splashing furnace protection. In converters, slag splashing furnace protection technology is widely used, and the furnace life can reach more than 10,000 times; There are many types of off-site refining furnaces. The insert tube lining of the RH method and DH method degassing device is generally cast as a whole with high-aluminum refractory castables, and the service life is 20~80 times. Ladles and tundishes are important auxiliary equipment of steelmaking furnaces and are also 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 10~70 times. When ladle blowing or continuous ingot casting is used, the ladle life decreases sharply due to the 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, which is lined with aluminum-magnesium castables and self-flowing materials, with a ladle age of about 95 times and 80 times respectively; A steel plant uses a 300t ladle for converter, which is lined with high-purity aluminum-magnesium castables. 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 China use aluminum-magnesium refractory castables with new technology for ladles not larger than 100t, with a ladle age of about 90 times, and a steel casting cost of 5.50~7.50 yuan per ton of steel. The lining of the tundish 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. The part above the slag line is made of high-alumina refractory castable, and the part from the slag line to the nozzle is made of low-cement corundum refractory castable, which are vibration-formed into an integral wrapped lining.

(II) Ironmaking system

The ironmaking system includes sintering, coking and blast furnace and its ancillary equipment. The belt sintering machine ignition furnace is made on-site with refractory plastic and clay combined with refractory castables, or hoisted with prefabricated blocks of phosphoric acid refractory castables, 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 are improved. Lightweight high-strength refractory castables or refractory fibers and their products can be used as linings, and better results can be obtained; The insulation layer, covering layer and furnace door of the coke oven roof are poured with refractory castables. When the furnace head is damaged, it is repaired with spray coating. In addition, the dry quenching equipment also uses heavy or lightweight refractory castables; The blast furnace is a continuous production ironmaking equipment. Small blast furnaces used to be hoisted and built with prefabricated blocks of aluminate cement and high-aluminum phosphate refractory castables, and now resin-bonded aluminum-carbon unburned bricks are commonly used for masonry. The water-cooled walls of large blast furnaces are made of silicon carbide castables, the furnace bottom pads and surrounding brick joints are made of refractory castables and silicon nitride fillers. When the furnace lining is damaged, it is repaired with refractory pressed materials and refractory spray coatings to extend the service life and make the furnace life reach 10 or even 15 years. The taphole of a blast furnace is usually blocked with loose Al2O3-SiC-C taphole mud, which can ensure stable tapping and normal operation. The taphole of a blast furnace was originally made of refractory ramming material, and the consumption of ton of iron in the taphole was about 1.1kg. Now it is cast with low-porosity dense refractory materials, and the amount of iron passing at one time reaches about 100,000 tons. The cumulative amount of iron passing in a generation of tapholes is about 900,000 tons, and the consumption of ton of iron in refractory materials is less than 0.38kg. At the same time, self-flowing refractory castables and non-baking refractory castables are also used on the taphole hook of the blast furnace. 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 refractory castable prefabricated blocks. The burner of the hot blast furnace can be built with refractory castable prefabricated blocks or poured on site, and its 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 is applied to the furnace body of a large hot blast furnace, and a layer of acid-resistant spray coating is sprayed on the top of the ball to form an integral lining. Corundum refractory castables and other materials are used for on-site pouring, which has achieved good results. Torpedo-type molten iron tanks and mixing furnaces generally use refractory castables partially or completely, and can also be repaired with refractory spray coatings, with good results.

(III) Building materials system

The building materials system includes industrial sectors such as cement, glass and ceramics. The lining of cement kilns uses high-alumina phosphate or magnesium and magnesium-chrome unfired bricks with a service life of 6 to 18 months, and amorphous refractory materials are also used locally. In the rotary kiln of a large cement plant, the use of refractory castables is 19% to 35%, 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 a new tank kiln is insulated, silicon insulation castables are generally used; kilns in the ceramic industry sometimes use silicon carbide refractory castables and lightweight refractory castables.

(IV) Steel rolling system

There are many types and large numbers of industrial furnaces in the steel rolling system. The operating temperature is generally below 1400℃, and all of them are flame furnaces. The kilns in this system can all be lined with amorphous refractory materials and achieve good economic results. The steel rolling heating furnace uses refractory plastic as the lining, which has a long service life. The lining is casted integrally with clay combined with refractory castables, and the service life is generally 4 to 10 years. For the regenerative heating furnace, micro-expansion refractory castables should be used as the lining, which 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 linings are used for 2 to 5 months, and those with adhesive combined 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 refractory castables with high aluminum content and high strength have poor thermal shock resistance and are prone to peeling and cracking during use, which affects their lifespan.

(V) 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 are used at a temperature of 600~1500℃. Generally, aluminate cement refractory castables, low cement refractory castables and corundum castables are used, 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.