Effect of andalusite on properties of bauxite-based low creep high alumina brick
In order to realize the low carbon, energy saving, high efficiency and high air temperature, long life and large scale of blast furnace hot blast stove, higher requirements are put forward for the performance of refractory materials for hot blast stove. Bauxite-based homogeneous material through homogenization sintering, uniform microstructure distribution, with stable chemical properties, mechanical properties, andalusite has good chemical stability, volume stability, high temperature mechanical strength and thermal shock resistance. The addition of andalusite to the bauxite-based homogeneous material can improve and enhance the high-temperature performance of bauxite-based low-creep high-alumina bricks and meet the use requirements of low-creep high-alumina bricks for key parts of hot blast stoves.
In this paper, the effect of the addition form of andalusite and sintering temperature on the performance of bauxite-based low creep high alumina bricks is studied. The chemical composition of raw materials is shown in Table 1.
The raw materials are 55 andalusite, 80 bauxite-based homogeneous material and Guangxi white mud. During the sintering process, andalusite is broken down into mullite and amorphous SiO or high silica glass phase (when there are impurities), and the surplus Al2O can generate secondary mullite in situ, accompanied by a certain volume expansion, with good creep resistance and thermal shock resistance. Bauxite-based homogeneous material is made of bauxite ore as raw material, through batching, homogenization, fine grinding, molding, high temperature calcination and other processes, with dense and uniform structure, uniform composition, stable performance characteristics.
The test scheme is shown in Table 2.
The sample is sintered at 1450 degrees C, 1500 degrees C and 1550 degrees C, the load softening temperature is shown in Figure 1, and the sample is tested for pressure creep after burning at 1550 degrees C, and the creep rate is shown in Figure 2.
As can be seen from Figure 1:
1. In the bauxite-based low creep high alumina brick, increasing the sintering temperature can improve the load softening temperature.
2, in the bauxite-based homogeneous material to add andalusite, can significantly improve the load softening temperature.
3. In the bauxite-based low creep high alumina brick, the addition of andalusite in the form of fine powder is better than that in the form of particles.
It can be seen from Figure 2 that adding andalusite to the bauxite-based homogeneous material can significantly improve the creep resistance, and the improvement effect of andalusite fine powder is better than that of andalusite particles.