Refractory aggregates are classified into clay, high alumina, corundum, silica, magnesia, magnesium aluminum spinel refractory aggregate, etc.

Refractory aggregates are refractory materials that play a role as a framework in the particle size composition of refractory materials. They are made of various refractory raw materials through calcination, crushing processing or artificial synthesis, with a particle size greater than O. 088mm granular material. Aggregate is the main material in amorphous refractory materials, and generally accounts for 60% to 75% of the total composition. Therefore, the materials of unshaped refractory materials are generally named after the aggregate materials used, such as refractory castables or refractory ramming materials using high-alumina bauxite clinker as aggregates, called high-aluminum castables or High aluminum ramming material.

Classification

By porosity：

According to the porosity, it can be pided into dense aggregate (also called heavy aggregate) and light aggregate (also called porous aggregate). Dense aggregate refers to aggregate with a porosity not greater than 30%. Dense aggregate can be pided into special dense aggregate (porosity≤3%), high dense aggregate (porosity 3%～10%) and ordinary dense aggregate (porosity 10%～30%). Lightweight aggregate refers to aggregate with a porosity greater than 45%. Lightweight aggregates can be pided into ordinary lightweight aggregates (porosity ratio 45% to 80%), ultra-lightweight aggregates (porosity ratio >80%) and special lightweight aggregates (such as alumina, zirconia hollow spheres).

By granularity:

Granularity In the production of amorphous refractory materials, it is generally pided into coarse-grained aggregate, medium-grained aggregate and fine-grained aggregate. The particle size range of coarse, medium and fine aggregates is related to the critical particle size (ie the maximum particle size) of the aggregates. For example, when the maximum particle size of the aggregate particles is 8mm, the coarse aggregate particle size ranges from 8 to 3mm, the medium aggregate particle size ranges from 3 to 1mm, and the fine aggregate particle size ranges from 1 to 0.088mm (or 0.074mm) ). Less than 0.088mm (or 0.074mm) is not called aggregate, but is called powder (or matrix). Another example is the maximum aggregate particle size is 3.5mm, the coarse aggregate particle size range is 3.5 ~ 1.5mm, the medium aggregate particle size is 1.5 ~ 0.5mm, the fine aggregate particle size is 0 .5 ~ 0.074mm. The ideal aggregate particle gradation should be able to achieve the closest packing, that is, the voids left after the coarse particles are in contact with each other are filled with medium particles, and the small voids left after the medium particles are filled are filled with fine particles. A skeleton is formed, and the remaining voids are filled with powder. However, since the particle shape of it is very irregular, it is difficult to obtain the ideal aggregate particle gradation in actual production. Aggregate grading is usually determined by experiment. The ratio of coarse, medium and fine aggregate is (35～45): (30～40): (15～25).

Application

⑴ Aluminum smelting industry. Used in national defense, aviation, automobiles, electrical appliances, chemicals, daily necessities, etc.

⑵Precision casting. The bauxite clinker is processed into fine powder to make a mold and then cast accurately. Used in military, aerospace, communications, instrumentation, machinery and medical equipment departments.

⑶ For refractory products. The high bauxite clinker has a fire resistance of up to 1780°C, strong chemical stability and good physical properties.

⑷Aluminosilicate refractory fiber. It has the advantages of light weight, high temperature resistance, good thermal stability, low thermal conductivity, small heat capacity and resistance to mechanical vibration. Used in various industries such as steel, nonferrous metallurgy, electronics, petroleum, chemical industry, aerospace, atomic energy, national defense, etc. It puts high-aluminum clinker into a high-temperature electric arc furnace with a melting temperature of about 2000-2200℃. After high-temperature melting, high-pressure high-speed air or steam blowing and cooling, it becomes a white "cotton"-aluminum silicate Refractory fiber. It can be pressed into fiber blanket, board or woven into cloth instead of refractory bricks lining smelting, chemical, glass and other industrial high-temperature kilns. Firefighters can use refractory fiber cloth to make clothes.

⑸ Using magnesia and bauxite clinker as raw materials, adding appropriate binding agent, it is used to cast the overall barrel lining of the steel drum with good effect.

⑹Manufacture of various compounds that can make aluminum in bauxite cement, abrasive materials, ceramic industry and chemical industry.

Physical And Chemical Indicators