Effect of fused magnesia on the properties of bauxite based castable

This study uses high-grade bauxite, fused magnesia, and other raw materials to investigate the effect of the addition form and amount of fused magnesia on the performance of bauxite based castables. The high temperature flexural strength and post firing performance of the samples from 1000 ℃ to 1400 ℃ were tested. The results of magnesium ball manufacturers indicate that with the increase of the amount of fused magnesium sand added, the amount of magnesium aluminum spinel generated in the bauxite based castable after firing at 1550 ℃ increases; Compared with the addition of fused magnesia powder, the sample with fused magnesia particles generates less liquid phase and more magnesium aluminum spinel at high temperatures. After firing at 1550 ℃, the apparent porosity is higher and the strength is lower. At 1000 ℃, the high-temperature bending strength is relatively high, while at 1200 ℃, the high-temperature strength decreases due to the formation of a liquid phase. At 1400 ℃, there is basically no high-temperature strength due to the formation of a large amount of liquid phase.

Refractory castable is the main type of amorphous refractory material, composed of aggregates with a certain particle size distribution, powder, binder, and additives. It has the advantages of simple production process, convenient construction, and long service life. Alumina based castables have excellent high-temperature strength, creep resistance, thermal shock resistance, high operating temperature, low production cost, and wide application range, and are often widely used as lining materials for thermal kilns and metallurgical equipment. By adding fine magnesia powder to bauxite based castable, it was found that with the addition of fine magnesia powder, the strength of the sample first increased and then decreased after drying, and the linear change rate after firing increased, but the strength decreased after firing. By adding SiO2 micropowder to the bauxite based castable, it was found that with the addition of SiO2 micropowder, the room temperature strength and high-temperature flexural strength of the sintered sample increased. Adding sillimanite to bauxite based castables, it was found that as the amount of sillimanite added increased, the room temperature strength and bulk density of the castables decreased. When the mass fraction of sillimanite added was 4%~8%, the comprehensive performance of the castables was better. This article studies the effects of different amounts and methods of adding fused magnesia on the sintering performance, room temperature performance, and high temperature performance of aluminum castables.

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