An alumina-chromium oxide sol-bonded chrome corundum brick and its preparation method

Abstract

The present invention belongs to the technical field of refractory materials, and particularly relates to an alumina-chromium oxide sol composite-bonded A12O3-Cr2O3 corundum brick and a preparation method thereof. The method comprises the following steps: Step 1: Preparation of the composite binder: A certain amount of ρ-Al2O3 fine powder, chromium oxide fine powder, and sodium tripolyphosphate are mixed evenly, and then aluminum dihydrogen phosphate and a certain mass of water are added for preparation; Step 2: After mixing corundum refractory aggregate, corundum fine powder, Cr2O3 fine powder, and α-Al2O3 fine powder, a certain amount of the alumina-chromium oxide sol composite binder described in Step 1 is added and stirred evenly, and finally, it is treated at a certain temperature to obtain. The alumina-chromium oxide sol composite-bonded A12O3-Cr2O3 corundum brick prepared by the said preparation method can provide high strength, good erosion resistance, strong slag corrosion resistance, and does not require high-temperature firing, only medium-temperature treatment at 600-800 °C is needed.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractories, and particularly relates to an alumina-chromium oxide sol composite-bonded Al2O3-Cr2O3 corundum brick and a preparation method thereof. Background Art

[0002] A teapot ladle is a container for holding molten steel in a foundry. Compared with traditional ladles, it is not equipped with a sliding gate flow control system. When pouring steel, the molten steel in the teapot ladle flows out from a pipeline assembled by segmented pipe bricks through tilting the ladle.

[0003] Since the tapping temperature of the electric furnace corresponding to the teapot ladle is very high, generally 1700°C - 1800°C, the pipe bricks not only have to withstand the thermal shock caused by a large temperature gradient, but also have to withstand the mechanical scouring of molten steel and the erosion of molten slag. The elbow pipe bricks at the turning points are damaged most severely, and their service life ultimately determines the service life of the teapot ladle. In serious cases, it will also cause molten steel leakage accidents. Therefore, it is of great significance to improve the high-temperature performance of the pipe bricks.

[0004] Ordinary corundum bricks usually use phosphoric acid-based or pulp waste liquor as binders. After forming and drying, the brick blanks need to be fired at a high temperature of 1600°C - 1700°C. Only after physical and chemical reactions inside the corundum bricks do they have the characteristics of high strength and good erosion resistance. However, on the one hand, due to environmental protection factors such as carbon emission reduction and energy consumption reduction, many refractory enterprises do not have high-temperature firing facilities with a firing temperature exceeding 1500°C; on the other hand, the anti-slag erosion performance of corundum bricks at high temperatures is poor. Al2O3 in the corundum bricks reacts with oxides such as CaO and SiO2 in the slag to produce low-melting phases, which are melted into the molten steel and slag, causing damage to the corundum bricks. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an alumina-chromium oxide sol composite-bonded Al2O3-Cr2O3 corundum brick with high strength, good erosion resistance, strong anti-slag erosion performance, and does not require high-temperature firing, only requires medium-temperature treatment at 600 - 800°C, and a preparation method thereof. When applied to the elbow of the pipe brick of the teapot ladle, its service life can be greatly improved, and the average service life of the teapot ladle is increased from the past 50 times to more than 80 times.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a preparation method of an alumina-chromium oxide sol composite-bonded Al2O3-Cr2O3 corundum brick, which is characterized by including the following steps:

[0007] Step 1: Preparation of the composite binder: Take a certain amount of ρ-Al2O3 fine powder, chromium oxide fine powder, and sodium tripolyphosphate, mix them evenly, and add aluminum dihydrogen phosphate and a certain mass of water to prepare it;

[0008] Step 2: Mix the corundum refractory aggregate, corundum fine powder, Cr2O3 fine powder, and α-Al2O3 fine powder, add a certain amount of the alumina-chromium oxide sol composite binder described in Step 1, stir evenly, form by mechanical pressing, cure, and finally treat at a certain temperature to obtain the product.

[0009] Further, the particle sizes of the ρ-Al2O3 fine powder and chromium oxide fine powder described in Step 1 are below 5 microns.

[0010] Further, the contents of the components described in Step 1 are: ρ-Al2O3 fine powder 40 - 45 wt%, chromium oxide fine powder 45 - 50 wt%, sodium tripolyphosphate 1 - 2 wt%, aluminum dihydrogen phosphate 7 - 8 wt%, and add a certain mass of water to prepare a sol binder with a specific gravity of 1.6 - 1.8.

[0011] Further, the contents of the components described in Step 1 are: ρ-Al2O3 fine powder 41 wt%, chromium oxide fine powder 50 wt%, sodium tripolyphosphate 1 wt%, aluminum dihydrogen phosphate 8 wt%, and a certain amount of water;

[0012] Further, in Step 2, corundum refractory aggregate 70 - 85 wt%, corundum fine powder 0 - 25 wt%, Cr2O3 fine powder 2 - 10 wt%, α-Al2O3 fine powder 0 - 5 wt%;

[0013] Further, the addition amount of the alumina-chromium oxide sol composite binder in Step 2 is 6 - 10 wt%;

[0014] Further, the addition amount of the alumina-chromium oxide sol composite binder in Step 2 is 8 wt%;

[0015] Further, the treatment temperature in Step 2 is 600°C - 800°C;

[0016] Further, the present invention provides a corundum brick obtained by the above preparation method.

[0017] The beneficial effects of the present invention are:

[0018] 1. Compared with the corundum bricks using phosphoric acid or paper mill waste liquor as binders, the corundum bricks of the present invention use a prefabricated sol binder. The micron-sized and sub-micron Al2O3 in the sol has the characteristics of high reaction activity with Cr2O3 and easy sintering. When treated at 600°C - 800°C, it endows the corundum with high sintering strength.

[0019] 2. Due to the use of alumina-chromium oxide sol composite binder in the corundum brick of the present invention, ultrafine Al2O3 particles and Cr2O3 particles in the binder will react to form a solid solution at high temperatures. Therefore, this corundum brick has high strength and good impact resistance performance.

[0020] 3. Due to the use of alumina-chromium oxide sol composite binder in the corundum brick of the present invention, the Cr2O3 micropowder is more evenly distributed in the matrix. Utilizing the characteristic that Cr2O3 is not easily infiltrated by molten slag, the slag penetration resistance and erosion resistance of the corundum brick are improved.

[0021] In summary, the corundum brick using alumina-chromium oxide sol composite binder has the characteristics of low firing temperature, good erosion resistance and strong erosion resistance. Compared with the original ordinary corundum brick, its service life has been greatly improved. The service life of the elbow pipe brick and the service life of the teapot ladle have been increased from the previous 50 times to more than 80 times, and the steel leakage accident caused by the damage of the elbow pipe brick has been effectively avoided. Specific Embodiments

[0022] The embodiments of the present invention will be described in detail below. The examples are shown in the accompanying drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0023] Example 1:

[0024] A kind of alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick and its preparation method: Preparation of alumina-chromium oxide sol composite binder: Take 45% of ρ-Al2O3 micropowder, 47% of chromium oxide micropowder, 1% of sodium tripolyphosphate, mix them evenly, and add 7% of aluminum dihydrogen phosphate and a certain mass of water to prepare a sol binder with a specific gravity of 1.7;

[0025] Mix the fused white corundum aggregate with a particle size of 3-1mm, the fused white corundum aggregate with a particle size of 1-0mm, the corundum fine powder with a particle size <88μm (Al2O3 content ≥ 95wt%), the Cr2O3 micropowder with a particle size <5μm (Cr2O3 content ≥ 95wt%) and the α-Al2O3 micropowder with a particle size <5μm (Al2O3 content ≥ 97wt%) respectively according to 50wt%, 25wt%, 10wt%, 10wt%, 5wt%, mix them evenly, and then add 6wt% of the alumina-chromium oxide sol composite binder of the above materials and mix. After stirring evenly, it is formed by machine pressing. After the formed green body is placed at room temperature for 6 hours, it is dried at 130°C for 18 hours, and then treated at 700°C to obtain a corundum elbow pipe brick.

[0026] Example 2

[0027] An alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick and its preparation method:

[0028] Preparation of the alumina-chromium oxide sol composite binder: Take 41% of ρ-Al2O3 fine powder, 50% of chromium oxide fine powder, 1% of sodium tripolyphosphate, mix them evenly, and add 8% of aluminum dihydrogen phosphate and a certain mass of water to prepare a sol binder with a specific gravity of 1.7;

[0029] Mix the fused white corundum aggregate with a particle size of 3-1mm, the fused white corundum aggregate with a particle size of 3-1mm, the corundum fine powder with a particle size <88μm (Al2O3 content ≥ 95wt%), the Cr2O3 fine powder with a particle size <5μm (Cr2O3 content ≥ 95wt%), and the α-Al2O3 fine powder with a particle size <5μm (Al2O3 content ≥ 97wt%) at 40wt%, 35wt%, 15wt%, 5wt%, and 5wt% respectively. After mixing evenly, add 6wt% of the above alumina-chromium oxide sol composite binder and mix. After stirring evenly, press and form by machine. After the formed green body is placed at room temperature for 6 hours, it is dried at 130°C for 18 hours, and then treated at 700°C to obtain a corundum elbow pipe brick.

[0030] Example 3

[0031] An alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick and its preparation method:

[0032] Preparation of the alumina-chromium oxide sol composite binder: Take 41% of ρ-Al2O3 fine powder, 50% of chromium oxide fine powder, 1% of sodium tripolyphosphate, mix them evenly, and add 8% of aluminum dihydrogen phosphate and a certain mass of water to prepare a sol binder with a specific gravity of 1.7;

[0033] Mix the fused white corundum aggregate with a particle size of 3-1mm, the fused white corundum aggregate with a particle size of 1-0mm, the corundum fine powder with a particle size <88μm (Al2O3 content ≥ 95wt%), the Cr2O3 fine powder with a particle size <5μm (Cr2O3 content ≥ 95wt%), and the α-Al2O3 fine powder with a particle size <5μm (Al2O3 content ≥ 97wt%) at 40wt%, 35wt%, 15wt%, 5wt%, and 5wt% respectively. After mixing evenly, add 8wt% of the above alumina-chromium oxide sol composite binder and mix. After stirring evenly, press and form by machine. After the formed green body is placed at room temperature for 6 hours, it is dried at 130°C for 18 hours, and then treated at 700°C to obtain a corundum elbow pipe brick.

[0034] Example 4

[0035] An alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick and its preparation method:

[0036] Preparation of the alumina-chromium oxide sol composite binder: Take 41% of ρ-Al2O3 fine powder, 50% of chromium oxide fine powder, and 1% of sodium tripolyphosphate, mix them evenly, and add 8% of aluminum dihydrogen phosphate and a certain mass of water to prepare a sol binder with a specific gravity of 1.7;

[0037] Mix the fused white corundum aggregate with a particle size of 3-1 mm, the fused white corundum aggregate with a particle size of 1-0 mm, the corundum fine powder with a particle size <88 μm (Al2O3 content ≥ 95 wt%), the Cr2O3 fine powder with a particle size <5 μm (Cr2O3 content ≥ 95 wt%), and the α-Al2O3 fine powder with a particle size <5 μm (Al2O3 content ≥ 97 wt%) at 50 wt%, 25 wt%, 10 wt%, 10 wt%, and 5 wt% respectively. After mixing evenly, add 10 wt% of the above alumina-chromium oxide sol composite binder based on the above materials and mix well. After stirring evenly, press it into shape by machine. After the formed green body is placed at room temperature for 6 hours, it is dried at 130°C for 18 hours, and then treated at 700°C to obtain a corundum elbow pipe brick.

[0038] Example 5

[0039] An alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick and its preparation method:

[0040] Preparation of the alumina-chromium oxide sol composite binder: Take 41% of ρ-Al2O3 fine powder, 50% of chromium oxide fine powder, and 1% of sodium tripolyphosphate, mix them evenly, and add 8% of aluminum dihydrogen phosphate and a certain mass of water to prepare a sol binder with a specific gravity of 1.7;

[0041] Mix the fused white corundum aggregate with a particle size of 3-1 mm, the fused white corundum aggregate with a particle size of 1-0 mm, the corundum fine powder with a particle size <88 μm (Al2O3 content ≥ 95 wt%), the Cr2O3 fine powder with a particle size <5 μm (Cr2O3 content ≥ 95 wt%), and the α-Al2O3 fine powder with a particle size <5 μm (Al2O3 content ≥ 97 wt%) at 45 wt%, 30 wt%, 23 wt%, 2 wt%, and 0 wt% respectively. After mixing evenly, add 8 wt% of the above alumina-chromium oxide sol composite binder based on the above materials and mix well. After stirring evenly, press it into shape by machine. After the formed green body is placed at room temperature for 6 hours, it is dried at 130°C for 18 hours, and then treated at 700°C to obtain a corundum elbow pipe brick.

[0042] Example 6

[0043] An alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick and its preparation method:

[0044] Preparation of the alumina-chromium oxide sol composite binder: Take 41% of ρ-Al2O3 fine powder, 50% of chromium oxide fine powder, and 1% of sodium tripolyphosphate, mix them evenly, and add 8% of aluminum dihydrogen phosphate and a certain mass of water to prepare a sol binder with a specific gravity of 1.7;

[0045] Mix the fused white corundum aggregate with a particle size of 3 - 1 mm, the fused white corundum aggregate with a particle size of 1 - 0 mm, the corundum fine powder with a particle size < 88 μm (Al2O3 content ≥ 95 wt%), the Cr2O3 fine powder with a particle size < 5 μm (Cr2O3 content ≥ 95 wt%), and the α-Al2O3 fine powder with a particle size < 5 μm (Al2O3 content ≥ 97 wt%) at 35 wt%, 35 wt%, 15 wt%, 10 wt%, and 5 wt% respectively. After mixing evenly, add 8 wt% of the above alumina-chromium oxide sol composite binder and mix. After stirring evenly, press and form by machine. After the formed green body is placed at room temperature for 6 hours, it is dried at 130 °C for 18 hours, and then treated at 700 °C to obtain a corundum elbow pipe brick.

[0046] Comparative example

[0047] Mix the fused white corundum aggregate with a particle size of 3 - 1 mm, the fused white corundum aggregate with a particle size of 1 - 0 mm, the corundum fine powder with a particle size < 88 μm (Al2O3 content ≥ 95 wt%), the Cr2O3 fine powder with a particle size < 5 μm (Cr2O3 content ≥ 95 wt%), and the α-Al2O3 fine powder with a particle size < 5 μm (Al2O3 content ≥ 97 wt%) at 55 wt%, 20 wt%, 21 wt%, 2 wt%, and 2 wt% respectively. After mixing evenly, add 6 wt% of the pulp waste liquor binder of the above materials and mix. After stirring evenly, press and form by machine. After the formed green body is placed at room temperature for 24 hours, it is dried at 120 - 140 °C for 24 hours, and then heat-treated at 1600 °C for 24 hours. A corundum elbow pipe brick with an apparent porosity of 18 - 20% and a bulk density of 3.15 - 3.20 g / cm 3 and a compressive strength of 60 - 100 Mpa can be obtained.

[0048] Performance test results of the sol-bonded corundum brick

[0049] Table 1 Performance test results of the sol-bonded corundum brick in the example

[0050]

[0051] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any respect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A preparation method of an alumina-chromium oxide sol composite-bonded Al2O3-Cr2O3 corundum brick, Characterized in that, comprising the following steps: Step 1: Preparation of the composite binder: Take a certain amount of ρ-Al2O3 fine powder, chromium oxide fine powder, and sodium tripolyphosphate, mix them evenly, and add aluminum dihydrogen phosphate and a certain mass of water to prepare it; Step 2: After mixing corundum refractory aggregate, corundum fine powder, Cr2O3 fine powder, and α-Al2O3 fine powder, add a certain amount of the composite binder described in Step 1, stir evenly, form by mechanical pressing, cure, and finally treat at a certain temperature to obtain it; The particle sizes of the ρ-Al2O3 fine powder and the chromium oxide fine powder described in Step 1 are below 5 microns; The contents of the components in Step 1 are: ρ-Al2O3 fine powder 40 - 45 wt%, chromium oxide fine powder 45 - 50 wt%, sodium tripolyphosphate 1 - 2 wt%, aluminum dihydrogen phosphate 7 - 8 wt%, and add a certain mass of water to prepare a composite binder with a specific gravity of 1.6 - 1.

8.

2. A preparation method of an alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick as described in claim 1, characterized in that: The contents of the components in Step 1 are: ρ-Al2O3 fine powder 41 wt%, chromium oxide fine powder 50 wt%, sodium tripolyphosphate 1 wt%, aluminum dihydrogen phosphate 8 wt%, and add a certain mass of water to prepare a composite binder with a specific gravity of 1.

7.

3. A preparation method of an alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick as described in claim 1, characterized in that: In Step 2, corundum refractory aggregate 70 - 85 wt%, corundum fine powder 0 - 25 wt%, Cr2O3 fine powder 2 - 10 wt%, α-Al2O3 fine powder 0 - 5 wt%.

4. A preparation method of an alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick as described in claim 1, characterized in that: The addition amount of the composite binder in Step 2 is 6 - 10 wt%.

5. A preparation method of an alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick as described in claim 1, characterized in that: The addition amount of the composite binder in Step 2 is 8 wt%.

6. A preparation method of an alumina-chromium oxide sol composite bonded Al2O3-Cr2O3 corundum brick as described in claim 1, characterized in that: The treatment temperature described in Step 2 is 600°C - 800°C.

7. A corundum brick prepared by using the preparation method of the alumina-chromium oxide sol composite-bonded Al2O3-Cr2O3 corundum brick according to any one of claims 1 - 6.

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