Fused cast low-silica low-soda azs brick and its preparation method

Abstract

This invention provides a cast low-silicon, low-sodium AZS brick, characterized by comprising the following raw materials: alumina, zirconium dioxide, silicon dioxide, chromium oxide, niobium pentoxide, magnesium oxide, barium oxide, and soda ash; wherein the mass ratio of niobium pentoxide to chromium oxide is 2-4:1. The cast low-silicon, low-sodium AZS brick of this invention, by introducing barium oxide, magnesium oxide, and sodium oxide into its composition system, and introducing niobium pentoxide and chromium oxide into the glass phase, reduces the glass phase content, increases corrosion resistance, reduces the amount of glass phase exudation, and extends the service life of the product in glass furnaces.

Description

Technical Field

[0001] This invention relates to the technical field of refractory materials, specifically to a cast low-silicon, low-sodium AZS brick and its preparation method. Background Technology

[0002] Fused cast zirconia-corundum bricks are mainly used in glass furnaces. They are fused cast refractory materials based on the Al2O3-ZrO2-SiO2 system, produced by high-temperature melting in an electric arc furnace, casting, and annealing cooling. With the upgrading of glass enterprises, the quality requirements for fused cast zirconia-corundum bricks are becoming more stringent. Defects in the quality of fused cast zirconia-corundum bricks directly affect the service life of glass furnaces. In the melting section of a glass tank furnace, the parts in contact with molten glass include: the feeding tank, tank walls, tank bottom, ear tanks, and molten glass separation equipment. These parts are not only subject to the erosion of molten glass but also to the chemical corrosion of the batch materials. Therefore, the selected materials need to have strong resistance to molten glass erosion, low contamination of the molten glass, and good thermal shock resistance to adapt to temperature changes under different operating conditions. Thus, fused cast zirconia-corundum bricks with high ZrO2 content are usually selected.

[0003] Existing 33# fused zirconia-corundum bricks are mainly used in the tank walls of glass furnaces. They contain 32.5% zircon, 1.5% sodium, and 16% silicon. The process involves mixing 48.4% zircon sand, 49.4% alumina powder, and 2.2% soda ash, then adding the mixture to a dedicated electric arc furnace. After melting by electrode heating, the mixture is poured into sand molds, annealed, and then cut and ground into finished products. The high silicon and sodium content in these fused zirconia-corundum bricks results in an unbalanced crystal phase composition, leading to product defects. During production, the high silicon content also causes mullite formation, a detrimental factor that affects the product's yield. Using the existing formula and process, the 33# fused zirconia-corundum bricks have a glass phase content exceeding 20%. During use in glass furnaces, this results in poor corrosion resistance, severe glass phase precipitation, damage to the crystal structure, peeling, corrosion, and a significantly reduced service life.

[0004] Therefore, a cast low-silicon, low-sodium AZS brick is needed to solve the above-mentioned technical problems, improve the product qualification rate, corrosion resistance, and extend the product's service life in glass furnaces. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a fused cast low-silicon, low-sodium AZS brick and its preparation method. This invention improves the product formulation and process technology, optimizes the crystal phase structure of the fused cast zirconia-corundum brick, enhances its corrosion resistance, and reduces the amount of glassy phase exudation, thereby extending the service life of the fused cast zirconia-corundum brick.

[0006] This invention is achieved through the following technical solution:

[0007] A cast low-silicon, low-sodium AZS brick comprises the following raw materials: alumina, zirconium dioxide, silicon dioxide, chromium oxide, niobium pentoxide, magnesium oxide, barium oxide, and soda ash; wherein the mass ratio of niobium pentoxide to chromium oxide is 2-4:1.

[0008] Furthermore, the mass ratio of magnesium oxide to barium oxide is 1-2.5:1.

[0009] Furthermore, the K2O content in the raw material oxides of the cast low-silicon, low-sodium AZS brick is ≤0.05.

[0010] Furthermore, the mass ratio of barium oxide to soda ash is 2-5:1.

[0011] Furthermore, the raw materials of the cast low-silicon, low-sodium AZS brick, by mass percentage, include 46.0-49.0% alumina, 35.5-38.5% zirconium dioxide, 8-11% silicon dioxide, 0.3-1.2% chromium oxide, 1.5-3.5% niobium pentoxide, 0.8-1.5% magnesium oxide, 0.5-1.2% barium oxide, and 0.1-0.3% soda ash.

[0012] A method for preparing the above-mentioned cast low-silicon, low-sodium AZS bricks includes the following steps: S1. Weigh each raw material according to the above mass percentages, mix them evenly, and obtain the mixture; S2. Add the obtained mixture to an electric arc furnace and heat it to melt. During the melting process, perform oxygen blowing at least once to obtain a molten liquid. S3. Pour the obtained molten material into a mold, heat and anneal to obtain cast low-silicon, low-sodium AZS bricks.

[0013] Furthermore, in step S2, the oxygen blowing treatment is carried out at 2700–2800°C.

[0014] Furthermore, in step S3, the temperature of the molten material during casting is 1850–1900°C.

[0015] Furthermore, in step S3, the annealing cooling rate is 5–50 °C / h.

[0016] Furthermore, the cast low-silicon, low-sodium AZS brick exhibits a static resistance to glass melt erosion at a rate ≤0.30 mm / 24h and a glass phase exudation rate ≤0.45%.

[0017] Through the above technical solution, this invention uses barium oxide as the main flux. Its low mobility increases the high-temperature viscosity of the glass phase, thereby suppressing exudation. Magnesium oxide partially dissolves into the ZrO2 lattice, enhancing high-temperature creep resistance, while the undissolved portion forms a microcrystalline phase with a dispersed distribution, strengthening grain boundary bonding. Sodium oxide promotes rapid melting of high-melting-point raw materials in the early stages of smelting and regulates the coefficient of thermal expansion of the glass phase. The synergistic effect of these three components achieves high-temperature stability and low exudation under low-silicon and low-sodium conditions. Niobium pentoxide and chromium oxide reduce the glass phase content, stabilize zirconium oxide, inhibit the transformation from tetragonal to monoclinic phase, refine and homogenize the eutectic structure, prevent the formation of low-melting-point impurity phases at grain boundaries, and reduce glass phase exudation.

[0018] The beneficial effects of this invention are: The fused cast low-silicon, low-sodium AZS brick of the present invention has excellent corrosion resistance. It produces very little glass phase during the production of high borosilicate glass, which can significantly extend the service life of refractory materials. The fused cast low-silicon, low-sodium AZS brick of the present invention introduces barium oxide, magnesium oxide, and sodium oxide into the composition system, and introduces niobium pentoxide and chromium oxide into the glass phase. This reduces the glass phase content, increases corrosion resistance, and also reduces the amount of glass phase exudation. Moreover, the product is stable and meets the requirements of industrial production. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] All reagents used in this invention are common reagents and can be purchased from conventional reagent manufacturing and sales companies.

[0021] Example 1 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 9.5%, chromium oxide 0.8%, niobium pentoxide 2.4%, magnesium oxide 1.2%, barium oxide 0.8%, and soda ash 0.2%; The specific process of its preparation is as follows: Weigh each raw material according to the above-mentioned mass percentages, mix them evenly to obtain a mixture; add the obtained mixture to an electric arc furnace and heat to melt, raise the furnace temperature to 2760℃, perform the first oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 4 minutes, let stand for 8 minutes, and then perform the second oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 3 minutes, to obtain molten material. After two oxygen blowings, the melt is well homogenized; pour the obtained molten material into a mold, the casting temperature is 1880℃, and hold for annealing to obtain cast low-silicon low-sodium AZS bricks.

[0022] Example 2 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 48.0%, zirconium dioxide 36.5%, silicon dioxide 9.0%, chromium oxide 0.5%, niobium pentoxide 2.0%, magnesium oxide 1.0%, barium oxide 1.0%, and soda ash 0.2%; The specific process of its preparation is as follows: Weigh each raw material according to the above-mentioned mass percentages, mix them evenly to obtain a mixture; add the obtained mixture to an electric arc furnace and heat to melt, raise the furnace temperature to 2760℃, perform the first oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 4 minutes, let stand for 8 minutes, and then perform the second oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 3 minutes, to obtain molten material. After two oxygen blowings, the melt is well homogenized; pour the obtained molten material into a mold, the casting temperature is 1880℃, and hold for annealing to obtain cast low-silicon low-sodium AZS bricks.

[0023] Example 3 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 46.5%, zirconium dioxide 38.0%, silicon dioxide 10.0%, chromium oxide 1.0%, niobium pentoxide 2.5%, magnesium oxide 0.9%, barium oxide 0.6%, and soda ash 0.15%; The specific process of its preparation is as follows: Weigh each raw material according to the above-mentioned mass percentages, mix them evenly to obtain a mixture; add the obtained mixture to an electric arc furnace and heat to melt, raise the furnace temperature to 2760℃, perform the first oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 4 minutes, let stand for 8 minutes, and then perform the second oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 3 minutes, to obtain molten material. After two oxygen blowings, the melt is well homogenized; pour the obtained molten material into a mold, the casting temperature is 1880℃, and hold for annealing to obtain cast low-silicon low-sodium AZS bricks.

[0024] Example 4 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.0%, zirconium dioxide 37.5%, silicon dioxide 8.5%, chromium oxide 0.6%, niobium pentoxide 1.8%, magnesium oxide 1.5%, barium oxide 0.7%, and soda ash 0.25%; The specific process of its preparation is as follows: Weigh each raw material according to the above-mentioned mass percentages, mix them evenly to obtain a mixture; add the obtained mixture to an electric arc furnace and heat to melt, raise the furnace temperature to 2760℃, perform the first oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 4 minutes, let stand for 8 minutes, and then perform the second oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 3 minutes, to obtain molten material. After two oxygen blowings, the melt is well homogenized; pour the obtained molten material into a mold, the casting temperature is 1880℃, and hold for annealing to obtain cast low-silicon low-sodium AZS bricks.

[0025] Example 5 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 48.5%, zirconium dioxide 35.5%, silicon dioxide 8.8%, chromium oxide 0.4%, niobium pentoxide 1.5%, magnesium oxide 0.8%, barium oxide 0.5%, and soda ash 0.1%; The specific process of its preparation is as follows: Weigh each raw material according to the above-mentioned mass percentages, mix them evenly to obtain a mixture; add the obtained mixture to an electric arc furnace and heat to melt, raise the furnace temperature to 2760℃, perform the first oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 4 minutes, let stand for 8 minutes, and then perform the second oxygen blowing, oxygen pressure 0.5MPa, oxygen blowing time 3 minutes, to obtain molten material. After two oxygen blowings, the melt is well homogenized; pour the obtained molten material into a mold, the casting temperature is 1880℃, and hold for annealing to obtain cast low-silicon low-sodium AZS bricks.

[0026] Comparative Example 1 A traditional AZS brick, by weight percentage, comprises the following raw materials: Alumina 49.0%, zirconium dioxide 35.0%, silicon dioxide 13.0%, sodium oxide 1.4%, the remainder being unavoidable impurities.

[0027] The raw materials do not contain chromium oxide, niobium oxide, magnesium oxide, or barium oxide; the specific process of its preparation method is the same as that in Example 1.

[0028] Comparative Example 2 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 9.5%, chromium oxide 0.8%, niobium pentoxide 2.4%, magnesium oxide 1.2%, barium oxide 0%, and soda ash 0.8%; The specific process of its preparation is the same as that in Example 1.

[0029] Comparative Example 3 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 14.0%, chromium oxide 0.8%, niobium pentoxide 2.4%, magnesium oxide 1.2%, barium oxide 0.8%, and soda ash 0.2%; The specific process of its preparation is the same as that in Example 1.

[0030] Comparative Example 4 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 9.5%, chromium oxide 0.8%, niobium pentoxide 2.4%, magnesium oxide 1.2%, barium oxide 0%, and soda ash 0.2%; The specific process of its preparation is the same as that in Example 1.

[0031] Comparative Example 5 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 9.5%, chromium oxide 1.6%, niobium pentoxide 0.8%, magnesium oxide 1.2%, barium oxide 0.8%, and soda ash 0.2%; The specific process of its preparation is the same as that in Example 1.

[0032] Comparative Example 6 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 9.5%, chromium oxide 1.6%, niobium pentoxide 0.8%, magnesium oxide 2.2%, barium oxide 0.3%, and soda ash 0.2%; The specific process of its preparation is the same as that in Example 1.

[0033] Comparative Example 7 A cast low-silicon, low-sodium AZS brick, comprising the following raw materials by weight percentage: Alumina 47.5%, zirconium dioxide 37.0%, silicon dioxide 9.5%, chromium oxide 1.6%, niobium pentoxide 0.8%, magnesium oxide 1.2%, barium oxide 0.3%, and soda ash 0.5%; The specific process of its preparation is the same as that in Example 1.

[0034] Effect Example The low-silicon, low-sodium AZS bricks prepared in Examples 1-5 and Comparative Examples 1-7 above, according to the Chinese building materials industry standard "Fused Cast Zirconia-Corundum Refractory Products for Glass Melting Furnaces" (JC493) 2001)) and GB / T2997 The test was conducted in 2015, and the results are shown in Tables 1 and 2.

[0035] Table 1. Performance of cast low-silicon, low-sodium AZS bricks prepared in Examples 1-5

[0036] Table 2. Properties of the cast AZS bricks prepared in Comparative Examples 1-7

[0037] As shown in Tables 1-2 above, the cast low-silicon, low-sodium AZS bricks prepared in Examples 1-5 of this invention have a static resistance to glass melt erosion rate ≤0.30 mm / 24h and a glass phase exudation amount ≤0.45%. Example 3 exhibits the best overall performance, with an erosion resistance rate as low as 0.22 mm / 24h and a glass phase exudation amount of only 0.2%, significantly improving both erosion resistance and exudation resistance compared to the conventional AZS brick in Comparative Example 1, and showing no crack defects. The conventional high-sodium, high-silicon AZS brick in Comparative Example 1 has a high glass phase content, an exudation amount of 2.5%, and produces many cracks after annealing. The high-sodium, barium-free AZS brick in Comparative Example 2 and the barium-free AZS brick in Comparative Example 4 demonstrate that barium oxide is indispensable.

[0038] In summary, the cast low-silicon, low-sodium AZS brick of the present invention has excellent erosion resistance, and produces very little glass phase during the production of high borosilicate glass, which can significantly extend the service life of refractory materials.

[0039] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fusion cast low-silica low-sodium AZS brick, characterized in that, The raw materials include alumina, zirconia, silica, chromium oxide, niobium pentoxide, magnesium oxide, barium oxide and soda ash; wherein the mass ratio of niobium pentoxide to chromium oxide is 2-4:

1.

2. The fused cast low silica low sodium AZS brick according to claim 1, characterized in that, The mass ratio of the magnesium oxide to the barium oxide is 1-2.5:

1.

3. The fusion cast low silica low sodium AZS tile according to claim 1, wherein, The K2O in the raw material oxides of the fused cast low-silica low-sodium AZS brick is ≤0.

05.

4. The fusion cast low silica low sodium AZS tile according to claim 1, wherein, The mass ratio of the barium oxide to the soda ash is 2-5:

1.

5. The fused cast low-silica low-soda AZS brick according to any one of claims 1 to 4, characterized in that, The raw materials include, in terms of mass percentage, 46.0-49.0% of alumina, 35.5-38.5% of zirconia, 8-11% of silica, 0.3-1.2% of chromium oxide, 1.5-3.5% of niobium pentoxide, 0.8-1.5% of magnesium oxide, 0.5-1.2% of barium oxide and 0.1-0.3% of soda ash.

6. A method of producing the fused cast low-silica low-soda AZS brick according to claim 5, characterized by, The method comprises the following steps: S1. The raw materials are weighed according to the above mass percentages, mixed uniformly to obtain a mixture; S2. The obtained mixture is added into an electric arc furnace for heating and melting, and at least one oxygen blowing treatment is performed during the melting process to obtain a molten liquid; S3. The obtained molten liquid is cast into a mold, and annealed to obtain the fused cast low-silica low-sodium AZS brick.

7. The method of producing a fusion cast low-silica low-sodium AZS tile according to claim 6, characterized in that, In step S2, the oxygen blowing treatment is performed at 2700-2800℃.

8. The method of producing a fusion cast low-silica low-sodium AZS tile according to claim 6, characterized in that, In step S3, when casting, the temperature of the molten liquid is 1850-1900℃.

9. The method of producing a fusion cast low-silica low-sodium AZS tile according to claim 6, characterized in that, In step S3, the annealing cooling speed is 5-50℃ / h.

10. The fusion cast low silica low sodium AZS tile according to claim 5, wherein, The fused cast low-silica low-sodium AZS brick has a glass liquid corrosion resistance of ≤0.30 mm / 24h under static state, and a glass phase exudation amount of ≤0.45%.

Images