CN1005841B - Method for manufacturing high-grade refractory product by adding kyanite - Google Patents

Abstract

Al of the invention₂Ｏ₃－ＳｉＯ₂The product is a refractory product, which is prepared by using high-alumina bauxite as a raw material and adding a certain amount of kyanite at 1550-1600 ℃ and has a high refractoriness under load and a low high-temperature creep rate.

Description

Method for manufacturing high-grade refractory product by adding kyanite

The invention relates to Al used in high-temperature kilns such as blast furnaces, hot blast stoves, electric furnaces, glass kilns and the like₂O₃-SiO₂Of refractory products, in particular Al₂O₃Refractory articles in an amount greater than 75% by weight.

In the existing Al produced by natural raw materials₂O₃-SiO₂In the refractory product, when Al is present₂O₃When the content is more than 75 wt%, the loaded softening point is 1520-1560 deg.C, and the high-temperature creep rate (1400 deg.C, 50 hr, load 2 kg/cm)²) Greater than 10%. If higher refractoriness under load and lower creep rate are required, it is necessary to use artificially synthesized mullite products, which are costly and complicated.

The present invention aims at producing artificial mullite product with technological indexes similar to those of high purity

Al of the invention₂O₃-SiO₂The refractory product comprises 75-85 wt% of bauxite clinker, 15-25 wt% of kyanite, a binder, a sulfite pulp waste liquid, and 3-5 wt% of bauxite clinker, Al₂O₃> 75% (wt.%), K₂O+Na₂O < 0.5 wt.%, particle size < 5mm, particles < 0.088mm > 35 wt.%. Kyanite concentrate powder, Al₂O₃More than or equal to 56 percent (weight percent) and the granularity is less than 0.2 mm. The ingredients are fully mixed in mixing equipment to form pug, and the pug has proper water content which is determined according to a forming method. And (5) molding by using a brick molding machine. The firing temperature is 1550-1600 ℃, and the heat preservation time is 50 hours.

Al of the invention₂O₃-SiO₂The main action principle of the product is that the phase change process of the kyanite at high temperature is fully utilized. The kyanite heating phase change product is mullite and high-silicon glass phase, and simultaneously has 12-16% volume expansion, but generally, the phase change process is incomplete and can only reach about 80% of a theoretical value. In addition, the finely dispersed corundum phase in the alumina clinker and the high-silicon glass phase of the kyanite heating phase-change product have a secondary mullite process, and the process is also accompanied with considerable volume expansion. The mullite generated by the two heating reactions forms a continuous crystal skeleton in the matrix, and simultaneously, the direct combination degree between high-temperature crystal phases is also improved, which is very beneficial to the high-temperature performance of the product.

The volume expansion in the above heating reaction can not only reduce the porosity of the product but also finely disperse the pores so that the through pores become closed pores. The mixture of kyanite concentrate powder and bauxite clinker particles in the product is in a non-uniform state combination in a microscopic scale, and the mixture is sintered but far from reaching a sintering equilibrium state, so that the product still has a transition trend from the non-equilibrium state to a final equilibrium state in a later heating process, and the trend is also beneficial to the high-temperature performance of the product.

Example (b):

alumina clinker containing Al₂O₃86.80 wt.%, K₂O+Na₂The crushed particles with O less than 0.5 wt.% pass through a 5mm sieve. The compounding ratio was 75% by weight. Kyanite Al₂O₃The content is 56.83% by weight and the compounding is 25% by weight. Adding sulfurous acid pulp waste liquid: 3% (by weight, specific gravity 1.17). The mud material comprises the following components in percentage by weight: more than 5mm3.6, 5-2 mm20.8, 2-0.5 mm16.4 and less than 0.07mm 46.6. The water content was 3.0%. And (5) molding by using a friction brick press. The bulk density of the green brick is 2.77g/cm³The apparent porosity was 20.7%.

The firing temperature of the product is 1600 ℃, and the heat preservation time is 50 hours

The main physical and chemical indexes of the product are as follows:

Al₂O₃（%） ≥80

apparent porosity (%) 13 to 15

Compressive strength kg/cm² 1300～1600

1630 to 1670 in refractoriness under load

Re-burning shrinkage of 1600-3 h (%) 0

Creep rate (%) 50hs-2kg/cm²

1400℃ 0.32

1500℃ 1.58

Claims (3)

1. Production of Al₂O₃-SiO₂A method of making a refractory article, characterized by: the raw material mixture ratio is 75-85% of bauxite clinker, 15-25% of kyanite concentrate powder (weight%) of binding agent, 3-5% of sulfurous acid paper pulp waste liquid (weight%) of external weight%, machine pressing and sintering at 1550-1600 ℃.

2. The method of claim 1, wherein: alumina clinker Al₂O₃A content of more than 75% by weight of K₂O+Na₂O content less than 0.5 wt%）。

3. The method of claim 1.2, wherein: kyanite concentrate powder Al₂O₃More than or equal to 56 percent (weight percent) and the particle size is less than 0.2 mm.