What are the classifications of refractory materials? What are the application fields of refractory materials?
Publish Time:
2023-07-11
I. What are Refractory Materials?
According to international standards, refractory materials are non-metallic materials (not excluding those containing a certain proportion of metal) and products whose chemical and physical properties remain stable and functional under high-temperature environments. The American standard for refractory materials defines them as non-metallic materials that, based on their chemical and physical properties, can be used to create structures and components in environments exceeding 1000℉. Japanese standards define refractory materials as shaped refractory materials usable at temperatures above 1500℃, and unshaped refractory materials, refractory slurries, and refractory insulating bricks with maximum usable temperatures above 800℃. China uses the international standard, defining refractory materials as non-metallic materials whose physical and chemical properties are suitable for use at high temperatures, but does not exclude products containing a certain amount of metallic materials.
II. What are the Types of Refractory Materials?
1. Refractory materials can be classified in several ways. By chemical properties, they are divided into three categories: acidic, basic, and neutral refractory materials.
2. Classified by the main mineral chemical components, they include: siliceous refractory materials, aluminosilicate refractory materials, magnesia refractory materials, magnesia spinel refractory materials, magnesia-chrome refractory materials, magnesia-dolomite refractory materials, dolomite refractory materials, carbon composite refractory materials, high-alumina refractory materials, chrome refractory materials, zirconia refractory materials, etc.
3. Classified by supply form, they are divided into shaped and unshaped refractory materials.
4. Classified by refractoriness, they are divided into ordinary/high-grade/special/super refractory materials; those withstanding 1580~1770℃ are called ordinary refractory materials; high-grade refractory materials can withstand 1770~2000℃; those withstanding 2000~3000℃ are called special refractory materials; and those above 3000℃ are called super refractory materials.
5. Classified by bulk density, they can be divided into lightweight and heavyweight refractory materials.
6. Classified by properties and dimensions, they are divided into standard/general/special/unique refractory materials, etc.
III. What are the Applications of Refractory Materials?
Refractory materials are basic materials for high-temperature industries such as iron and steel, non-ferrous metals, petrochemicals, building materials, and power generation, and are important supporting materials for high-temperature industrial thermal equipment. The four major downstream application areas are: the iron and steel industry, the cement industry, non-ferrous metal smelting processes, and the flat glass industry.
1. Area One: Iron and Steel Industry
70% of the downstream demand for refractory materials comes from the iron and steel industry, used in blast furnaces, converters, electric furnaces, steel ladles, LF furnaces, RH furnaces, and continuous casting systems, etc.
The steel production process involves smelting iron ore into pig iron in a blast furnace, then refining the molten iron into steel in a converter or electric furnace, and finally casting the molten steel into continuously cast billets or ingots, which are then processed into various types of steel products through rolling and other plastic deformation methods. Because the working environments and usage requirements of various furnaces in steel production differ, the requirements for refractory materials also vary.
2. Area Two: Cement Industry
Refractory bricks are widely used in various industrial sectors and high-temperature technology fields and are indispensable production materials in the clinker calcination process of cement plants. Alkaline and silico-aluminous refractory bricks are most commonly used in cement plants. Previously, magnesia-chrome bricks were most commonly used in the rotary kiln burning zone, but the pollution risk of water-soluble hexavalent chromium in magnesia-chrome bricks has become a major issue that needs to be addressed in the application of refractory bricks. With increasing environmental awareness, some industrialized countries (such as Germany and the United States) have enacted legislation to restrict the use of magnesia-chrome bricks. China also has corresponding regulations. Currently, chromium-free refractory materials are being implemented throughout the cement industry, and magnesia-iron and magnesia-calcium bricks can replace the original magnesia-chrome bricks in the burning zone.
Different parts of the clinker calcination and cooling systems in cement plants have different performance requirements for refractory bricks, and the types of refractory bricks used also vary. Commonly used refractory bricks in cement plants include: high-alumina bricks, dolomite bricks, magnesia-chrome bricks, spinel bricks, anti-spalling bricks, and silicon-molybdenum bricks, etc.
3. Area Three: Non-ferrous Metal Smelting Industry
The main equipment for non-ferrous metal smelting is non-ferrous metal smelting furnaces. The quality and selection of refractory materials are important factors in improving the service life and output of non-ferrous metal smelting furnaces. The structural form of the smelting furnace depends on different pyrometallurgical processes, and different furnace types are selected according to different smelting processes.
4. Area Four: Glass Industry
As the core equipment for glass production, the progress of kiln technology requires a variety of high-quality refractory materials as a guarantee, requiring the refractory materials to withstand higher temperatures, more drastic temperature changes, stronger chemical corrosion, and more severe stress damage. Only with the supporting application of a variety of high-quality refractory materials can the high efficiency, energy saving, and low pollution advantages of new kiln technologies be realized.
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