Corundum-mullite brick produced from recycled 95 alumina ceramics and its preparation method

Abstract

The present invention discloses a corundum-mullite brick produced from recycled 95 alumina ceramics and a preparation method thereof. The components of the corundum-mullite brick include, by weight percentage: 40-70% of recycled 95 alumina ceramics, 20-60% of a mixed powder, and 1-8% of a binder. The components of the mixed powder include, by weight percentage: 10-20% of sintered corundum, 5-20% of andalusite powder, 5-10% of kaolin powder, and 1-10% of calcined alumina fine powder. The recycled 95 alumina ceramics used in the present invention are industrial waste. Using it as the main raw material of the present invention reduces the linear expansion rate and apparent porosity of refractory products, improves the thermal shock stability and wear resistance coefficient, and also reduces the raw material cost of refractory materials, realizing the comprehensive utilization of waste, improving the resource utilization efficiency, and conforming to the environmental protection concept.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory materials, and particularly relates to a corundum-mullite brick produced by using recycled 95 alumina ceramics and a preparation method thereof. Background Art

[0002] Corundum-mullite bricks refer to refractory products composed mainly of corundum and mullite as the main crystal phases. Corundum-mullite bricks have a high service temperature, good corrosion resistance, and good thermal shock stability. However, corundum-mullite bricks have a large thermal expansion rate, and convex peeling phenomena are likely to occur on both longitudinal sides at the top during use. Moreover, the raw material cost of current corundum-mullite bricks is relatively high.

[0003] After various kilns and chromium equipment are disassembled, a large amount of waste corundum materials and waste alumina materials can be obtained. These recycled waste materials will cause a large amount of environmental pollution. If they can be effectively recycled and utilized, it will be an effective utilization method for green environmental protection production. Summary of the Invention

[0004] Object of the Invention: In order to overcome the deficiencies existing in the prior art, the present invention provides a corundum-mullite brick produced by using recycled 95 alumina ceramics and a preparation method thereof. The 95 alumina ceramics have a large bulk density, a low apparent porosity, good thermal shock stability, high compressive strength, and a small linear expansion rate, and can replace fused corundum to overcome the large linear expansion rate of the prior art and reduce costs, and produce a corundum-mullite brick with excellent comprehensive performance.

[0005] Technical Solution: To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The first object of the present invention is to provide a corundum-mullite brick produced by using recycled 95 alumina ceramics. The components of the corundum-mullite brick include, by weight percentage: 40-70% of recycled 95 alumina ceramics, 20-60% of mixed powder, and 1-8% of binder. The components of the mixed powder include, by weight percentage: 10-20% of sintered corundum, 5-20% of andalusite powder, 5-10% of kaolin powder, and 1-10% of calcined alumina fine powder.

[0007] The present invention uses recycled 95 alumina ceramics as the main component raw material of the corundum-mullite brick, uses recycled 95 alumina ceramics as the particle phase to replace the originally expensive corundum material, and uses the mixed powder formed by corundum, andalusite powder, kaolin powder, and calcined alumina fine powder as the matrix. On the premise of maintaining effective product performance, the raw material cost is effectively reduced, the production efficiency is increased, and it has broad application prospects.

[0008] In an embodiment of the present invention, the components of the recycled 95 alumina ceramics include, by weight parts: Al2O3≥94% and R2O≤0.2%.

[0009] In one embodiment of the present invention, the particle size of the recycled 95 alumina ceramic is ≤ 3 mm, and the bulk density is ≥ 3.6 g / cm 3 , the apparent porosity is ≤ 3.5%, and the water absorption rate is ≤ 1%.

[0010] The high-performance ceramic manufactured by spray granulation, isostatic pressing and high-temperature sintering processes from 95 alumina micropowder is called 95 alumina porcelain parts, which have the characteristics of high hardness, wear resistance and good corrosion resistance. The recycled 95 alumina ceramic additionally has the advantage of being economical and practical. Because of its large bulk density, low apparent porosity, good thermal shock stability, high compressive strength and small linear expansion rate, it can replace fused corundum and reduce costs.

[0011] In one embodiment of the present invention, the components of the corundum-mullite brick further include 5-20% by weight of fused mullite.

[0012] In one embodiment of the present invention, the components of the fused mullite include Al2O3 ≥ 68% and Fe2O3 ≤ 0.5% by weight.

[0013] In one embodiment of the present invention, the particle size of the fused mullite is ≤ 1 mm.

[0014] Mullite is a refractory raw material mainly composed of 3Al2O3·2SiO2 crystal phase. The methods for synthesizing mullite can be divided into sintering method and electrofusion method. The electrofusion method is to add the batch material into an electric arc furnace, melt it at the high temperature formed by the electric arc, and cool and crystallize to form fused mullite. Compared with sintered mullite, the crystal development of fused mullite is perfect, the crystal grains are large, the defects are few, and the crystal size is hundreds of times that of sintered mullite. Therefore, the high-temperature mechanical properties and erosion resistance are relatively better.

[0015] In one embodiment of the present invention, the components of the sintered corundum include Al2O3 ≥ 99% and Fe2O3 ≤ 0.2% by weight.

[0016] In one embodiment of the present invention, the particle size of the sintered corundum is ≤ 0.074 mm.

[0017] The microstructure of sintered corundum is a polycrystal of dense α-Al2O3, which is milky white, contains a very small amount of β-Al2O3, and does not contain glass phase.

[0018] In one embodiment of the present invention, the components of the andalusite powder include Al2O3 ≥ 56% and Fe2O3 ≤ 1.5% by weight.

[0019] In one embodiment of the present invention, the particle size of the andalusite powder is ≤ 1 mm.

[0020] Andalusite powder is grayish-brown, with vitreous luster, opaque, hardness 6.5 - 7.5, and specific gravity 3.15 - 3.16.

[0021] In one embodiment of the present invention, the components of the kaolin powder by weight include Al2O3 ≥ 15%, Fe2O3 ≤ 1.8%.

[0022] In one embodiment of the present invention, the particle size of the kaolin powder ≤ 0.088 mm.

[0023] Kaolin powder is also called kaolinite, off-white powder, soft and white in texture, density 2.54 - 2.60 mg / cm 3 , melting point about 1785 °C, good light resistance, and can be used as a binder for refractory materials.

[0024] In one embodiment of the present invention, the components of the calcined alumina micropowder by weight include Al2O3 ≥ 99.2%.

[0025] In one embodiment of the present invention, the particle size of the calcined alumina micropowder ≤ 0.005 mm.

[0026] The high-temperature calcined alumina micropowder uses a rotary kiln, the roasting temperature is about 1300 - 1400 °C, and it has the characteristics of high temperature resistance and wear resistance. Therefore, calcined alumina is generally used in the refractory material and ceramic industries. The processing difficulty of high-temperature calcined alumina is relatively lower compared to white fused alumina, and the processing cost is lower.

[0027] In one embodiment of the present invention, the binder is an organic or inorganic binder, including one or several of industrial phosphoric acid or aluminum dihydrogen phosphate and yellow dextrin.

[0028] In one embodiment of the present invention, the corundum-mullite brick prepared by the present invention by weight includes Al2O3 83% - 88%, SiO2 10% - 13%, Fe2O3 0.6% - 0.8%, P2O5 1% - 6%.

[0029] In one embodiment of the present invention, the bulk density of the corundum-mullite brick prepared by the present invention is 3.00 ± 0.20 g / cm 3 .

[0030] In one embodiment of the present invention, the compressive strength of the corundum-mullite brick prepared by the present invention is 120 - 180 Mpa.

[0031] In one embodiment of the present invention, the 0.2 Mpa load softening temperature of the corundum-mullite brick prepared by the present invention is 1620 - 1670 °C.

[0032] In one embodiment of the present invention, the apparent porosity of the corundum-mullite brick prepared by the present invention is 14-16%.

[0033] In one embodiment of the present invention, the linear expansion rate of the corundum-mullite brick prepared by the present invention at 1400 °C is 0.93%-0.95%.

[0034] In one embodiment of the present invention, the thermal shock resistance stability of the corundum-mullite brick prepared by the present invention is ≥25 times.

[0035] In one embodiment of the present invention, the abrasion resistance coefficient of the corundum-mullite brick prepared by the present invention is 6-8 CC.

[0036] Another object of the present invention is to provide a preparation method of a corundum-mullite brick produced by using recycled 95 alumina ceramics, comprising the following steps:

[0037] 1) Add the raw materials to a strong roller mixer and mix for 10-15 minutes to obtain a mixture;

[0038] 2) The mixture is aged for 12-24 hours and then remixed for 5 minutes;

[0039] 3) The mixture after remixing is pressed into a brick blank and dried at 80-180 °C for at least 24 hours, and calcined at 1480-1550 °C to obtain the corundum-mullite brick.

[0040] In one embodiment of the present invention, in step 3), the mixture after remixing is pressed into a brick blank by the method of hanging and exhausting air.

[0041] Beneficial effects: The corundum-mullite brick produced by using recycled 95 alumina ceramics and its preparation method provided by the present invention have the following advantages compared with the prior art: The recycled 95 alumina ceramics used in the present invention are industrial wastes. Using it as the main raw material of the present invention reduces the linear expansion rate and apparent porosity of refractory products, improves the thermal shock resistance stability and abrasion resistance coefficient, and also reduces the raw material cost of refractory materials, realizing the comprehensive utilization of waste, improving the resource utilization efficiency, and conforming to the environmental protection concept. Specific embodiments

[0042] The following further illustrates the present invention in conjunction with embodiments. According to the following embodiments, the present invention can be better understood. However, those skilled in the art can easily understand that the specific material ratios, process conditions and their results described in the embodiments are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0043] In the present invention, the raw materials involved are all commercially available conventional industrial raw materials; the processing methods involved, unless otherwise specified, are all conventional methods.

[0044] In the present invention, the test methods for the content of Al2O3, SiO2, Fe2O3, P2O5, bulk density, compressive strength, softening temperature under a load of 0.2 Mpa, apparent porosity, linear expansion rate at 1400 °C, thermal shock resistance stability and wear resistance coefficient, etc. are all determined by conventional methods.

[0045] Example 1:

[0046] Design a corundum-mullite brick produced from recycled 95 alumina ceramic parts, including the following raw materials in parts by weight: 60 parts of recycled 95 alumina ceramic parts, 40 parts of mixed powder (the mixed powder is composed of 19 parts of sintered corundum, 10 parts of andalusite powder, 6 parts of kaolin powder, and 5 parts of calcined alumina micropowder), and 5 parts of industrial phosphoric acid binder.

[0047] Recycled 95 alumina ceramic: The components include Al2O3: 94.5% and R2O 0.14% by weight, with a particle size ≤ 3 mm; the bulk density is 3.60 g / cm 3 , the apparent porosity ≤ 3.2%, the water absorption rate is 0.9%, and it is an industrial waste.

[0048] Sintered corundum: The components include Al2O3 99.4% and Fe2O3 0.16% by weight, with a particle size ≤ 0.074 mm;

[0049] Andalusite powder: The components include Al2O3 57.1% and Fe2O3 1.49% by weight, with a particle size ≤ 1 mm;

[0050] Kaolin powder: The components include Al2O3 18.3% and Fe2O 1.56% by weight, with a particle size ≤ 0.088 mm;

[0051] Calcined alumina micropowder: The components include Al2O3 99.3% by weight, with a particle size ≤ 0.005 mm;

[0052] Industrial phosphoric acid: The concentration is 60%, and the density is 1.42 g / cm 3 .

[0053] The preparation method of the above-mentioned corundum-mullite brick produced from recycled 95 alumina ceramic parts includes the following steps:

[0054] 1) The above raw materials are in a weight ratio of 60 parts of recycled 95 alumina ceramic parts, 40 parts of mixed powder (the mixed powder is composed of 19 parts of sintered corundum, 10 parts of andalusite powder, 6 parts of kaolin powder, and 5 parts of calcined alumina micropowder), and 5 parts of industrial phosphoric acid binder.

[0055] Add to a strong roller mixer and mix for 15 minutes to obtain a mixture;

[0056] 2) Age the mixture obtained in step 1) for 20 hours, and then re-grind the aged mixture for 5 minutes;

[0057] 3) Press the re-ground mixture into bricks by the method of hanging and exhausting air, dry it at 80 - 180 °C (the drying time is not less than 24 hours), and calcine it at 1500 °C to obtain corundum-mullite bricks.

[0058] The corundum-mullite bricks prepared in this example have an Al2O3 content of 84.65%, an SiO2 content of 12.04%, an Fe2O3 content of 0.79%, a P2O5 content of 2.89%, and a bulk density of 3.01 g / cm 3 , a compressive strength of 131 Mpa, a softening temperature under a load of 0.2 Mpa of 1622 °C, an apparent porosity of 15.2%, a linear expansion rate at 1400 °C of 0.946%, a thermal shock resistance stability of ≥ 25 times, and a wear resistance coefficient of 7.2 CC.

[0059] Example 2:

[0060] The difference from Example 1 is:

[0061] A corundum-mullite brick produced from recycled 95 alumina ceramic parts, comprising the following raw materials in parts by weight:

[0062] 50 parts of recycled 95 alumina ceramic parts, 10 parts of fused mullite, 40 parts of mixed powder (the mixed powder is composed of 19 parts of sintered corundum, 10 parts of andalusite powder, 6 parts of kaolin powder, and 5 parts of calcined alumina micropowder), and 6 parts of industrial phosphoric acid binder.

[0063] Fused mullite: Al2O3 ≥ 68%, Fe2O3 ≤ 0.5%, particle size ≤ 1 mm;

[0064] Industrial phosphoric acid concentration 85%, density 1.689 g / cm 3 .

[0065] The corundum-mullite bricks prepared by the present invention have an Al2O3 content of 85.01%, an SiO2 content of 11.76%, an Fe2O3 content of 0.68%, a P2O5 content of 4.9%, and a bulk density of 3.09 g / cm 3 , a compressive strength of 149 Mpa, a softening temperature under a load of 0.2 Mpa of 1647 °C, an apparent porosity of 14.1%, a linear expansion rate at 1400 °C of 0.938%, a thermal shock resistance stability of ≥ 25 times, and a wear resistance coefficient of 6.9 CC.

[0066] Example 3:

[0067] The difference from Example 1 is:

[0068] A corundum-mullite brick produced from recycled 95 alumina ceramic parts, comprising raw materials in the following parts by weight:

[0069] 60 parts of recycled 95 alumina ceramic parts, 40 parts of mixed powder (the mixed powder consists of 19 parts of sintered corundum, 10 parts of andalusite powder, 6 parts of clay powder, and 5 parts of calcined alumina micropowder), and 4 parts of aluminum dihydrogen phosphate binder.

[0070] The density of aluminum dihydrogen phosphate is 1.56 g / cm 3 .

[0071] The corundum-mullite brick prepared by the present invention has an Al2O3 content of 84.88%, an SiO2 content of 12.13, an Fe2O3 content of 0.69%, a P2O5 content of 1.35%, a bulk density of 3.16 g / cm 3 , a compressive strength of 165 Mpa, a 0.2 Mpa load softening temperature of 1666 °C, an apparent porosity of 14.5%, a linear expansion rate at 1400 °C of 0.94%, a thermal shock resistance stability of ≥ 25 times, and a wear resistance coefficient of 6.3 CC.

[0072] Example 4:

[0073] The difference from Example 1 is:

[0074] A corundum-mullite brick produced from recycled 95 alumina ceramic parts, comprising raw materials in the following parts by weight:

[0075] 65 parts of recycled 95 alumina ceramic parts, 35 parts of mixed powder (the mixed powder consists of 12 parts of sintered corundum, 10 parts of andalusite powder, 10 parts of clay powder, and 8 parts of calcined alumina micropowder), and 1 part of yellow dextrin binder.

[0076] The corundum-mullite brick prepared by the present invention has an Al2O3 content of 82.14%, an SiO2 content of 13.0, an Fe2O3 content of 0.66%, a P2O5 content of 0, a bulk density of 2.98 g / cm 3 , a compressive strength of 95 Mpa, a 0.2 Mpa load softening temperature of 1681 °C, an apparent porosity of 17.5%, a linear expansion rate at 1400 °C of 0.941%, a thermal shock resistance stability of 18 times, and a wear resistance coefficient of 9.1 CC.

[0077] The performance test results of the lightweight heat-insulating castable prepared from the materials of the above Examples 1-4 and the method of the present invention are shown in Table 1 below.

[0078] Table 1 Performance test of the lightweight heat-insulating castable prepared in Examples 1-4

[0079] Example 1 Example 2 Example 3 Example 4 <![CDATA[Al2O3 content / %]]> 84.65 85.01 84.88 82.14 <![CDATA[SiO2 content / %]]> 12.04 11.76 12.13 13.0 <![CDATA[Fe2O3 content / %]]> 0.79 0.68 0.69 0.66 <![CDATA[P2O5 content / %]]> 2.89 4.9 1.35 0 (excluding) <![CDATA[Volume density / kg / cm 3 > 3.01 3.09 3.16 2.98 Compressive strength / MPa 131 149 165 95 Softening temperature under 0.2 Mpa load / °C 1622 1647 1666 1681 Apparent porosity / % 15.2 14.1 14.5 17.5 Linear expansion rate at 1400 °C / % 0.946 0.938 0.94 0.941 Thermal shock resistance stability / times ≥25 ≥25 ≥25 18 Wear resistance coefficient / CC 7.2 6.9 6.3 9.1

[0080] As can be seen from the results in Table 1, the corundum-mullite bricks prepared by using recycled 95 alumina ceramics as the main raw material in Examples 1-4 have good compressive strength, small linear expansion rate, excellent thermal shock stability and low wear coefficient, and other properties are also comparable to those of corundum-mullite brick products on the market. Moreover, the recycled 95 alumina ceramics are lower in price and easier to obtain, greatly reducing the production cost of corundum-mullite bricks.

[0081] The present invention makes full use of the unique chemical composition stability and dense physical properties of 95 alumina ceramics, adopts a multi-granularity combination, and the prepared corundum-mullite bricks have main indexes superior to the existing ones. In particular, the thermal expansion rate is less than that of the existing products, which not only reuses the waste 95 alumina ceramics, but also reduces the raw material cost of refractory bricks.

[0082] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A corundum-mullite brick produced by using recycled 95 alumina ceramics, characterized in that, The components of the corundum-mullite brick include: 60 parts of recycled 95 alumina ceramics, 40 parts of mixed powder, and a binder. The binder is 5 parts of industrial phosphoric acid or 4 parts of aluminum dihydrogen phosphate. The components of the mixed powder include 19 parts of sintered corundum, 10 parts of andalusite powder, 6 parts of clay powder, and 5 parts of calcined alumina micropowder; The components of the recycled 95 alumina ceramic include, by weight, Al2O3 ≥ 94.5% and R2O ≤ 0.14%. The particle size of the recycled 95 alumina ceramic is ≤ 3 mm, and the bulk density is 3.6 g / cm 3 , the apparent porosity is ≤ 3.2%, and the water absorption rate is 0.9%; The particle size of the sintered corundum is ≤0.074 mm, the particle size of the andalusite powder is ≤1 mm, the particle size of the clay powder is ≤0.088 mm, and the particle size of the calcined alumina micropowder is ≤0.005 mm; The corundum-mullite brick contains, by weight, 84.65% of Al2O3, 12.04% of SiO2, 0.79% of Fe2O3, and 2.89% of P2O5. The bulk density of the corundum-mullite brick is 3.01 g / cm 3 , the compressive strength is 131 Mpa, the softening temperature under a load of 0.2 Mpa is 1622 °C, the apparent porosity is 15.2%, the linear expansion rate at 1400 °C is 0.946%, the thermal shock resistance stability is ≥ 25 times, and the wear resistance coefficient is 7.2 CC; or The corundum-mullite brick comprises, by weight, 84.88% of Al2O3, 12.13% of SiO2, 0.69% of Fe2O3, and 1.35% of P2O5. The bulk density of the corundum-mullite brick is 3.16 g / cm 3 , the compressive strength is 165 Mpa, the softening temperature under a load of 0.2 Mpa is 1666 °C, the apparent porosity is 14.5%, the linear expansion rate at 1400 °C is 0.94%, the thermal shock resistance stability is ≥ 25 times, and the wear resistance coefficient is 6.3 CC; The preparation method of the corundum-mullite brick produced by using recycled 95 alumina ceramics includes the following steps: 1) Add the raw materials into a strong rolling mixer and roll for 10 - 15 minutes to obtain a mixture; 2) Let the mixture be aged for 12 - 24 hours and then roll back for 5 minutes; 3) Press the rolled-back mixture into a brick blank, dry it at 80 - 180 °C for at least 24 hours, and calcine it at 1480 - 1550 °C to obtain the corundum-mullite brick.

2. The corundum-mullite brick according to claim 1, wherein, The components of the sintered corundum include, by weight, Al2O3 ≥ 99.0% and Fe2O3 ≤ 0.2%.

3. The corundum-mullite brick according to claim 1, characterized in that, The components of the andalusite powder include, by weight, Al2O3 ≥ 56% and Fe2O3 ≤ 1.5%.

4. The corundum-mullite brick according to claim 1, characterized in that, The components of the clay powder include, by weight, Al2O3 ≥ 15% and Fe2O3 ≤ 1.8%.

5. The corundum-mullite brick according to claim 1, characterized in that, The components of the calcined alumina micropowder include, by weight, Al2O3 ≥ 99.2%.

6. The corundum-mullite brick according to claim 1, characterized in that, The concentration of the industrial phosphoric acid is 60%, and the density is 1.42 g / cm 3 .

7. The corundum-mullite brick according to claim 1, characterized in that, The density of the aluminum dihydrogen phosphate is 1.56 g / cm 3 .