Corundum-mullite high-strength light brick and preparation process thereof

Abstract

The invention relates to a corundum-mullite high-strength light brick and a preparation process thereof.The preparation process comprises the steps that used waste sliding plate recycled material powder is adopted as a raw material, activated aluminum oxide powder, corundum fibers, metal aluminum and metal silicon-aluminum alloy are added, a composite gelling agent is adopted as a binding agent, a foaming agent, a foam stabilizer and a foam fixing agent are added, stirring and pouring are conducted, and a light brick blank is obtained; and drying and sintering to obtain the high-strength light brick which can be used at the temperature of 1450 DEG C or above and has the highest service temperature of 1600 DEG C.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and particularly relates to a corundum-mullite high-strength lightweight brick and a preparation process thereof. Background Art

[0002] my country produces more than 1 billion tons of steel every year. The slide plates that control the flow rate of molten steel in converters, ladles and continuous casting tundishes during the steelmaking process will have problems such as roughening, oxidation, hole expansion and cracking after several pulls and slides. New slide plates need to be replaced, and the replaced slide plates become industrial solid waste. At present, the disposal and recycling of waste slide plates requires a series of complex processes such as sorting, impurity removal, crushing, hydration, drying and screening. This treatment method occupies land and factory buildings as storage yards, and waste gas is generated during the hydration process, which pollutes the environment. The drying process also consumes a lot of fuel, and the recycled materials with low purity can only be used as downgraded raw materials, which are not economically practical.

[0003] The existing CN109133880A technology adopts a simple crushing process to prepare corundum mullite lightweight bricks from aluminum-carbon refractory solid waste. The patent puts solid waste particles with a particle size of less than 5 mm into a ball mill and grinds them for 24 to 36 hours at a water-solid ratio of 0.5 to 0.6 to make a slurry. The slurry is then added to a mixture of 20 to 30 wt% of the slurry weight, mullite lightweight material with a particle size of less than 1 mm and 0.5 to 2.0 wt% of the slurry weight. The mixture is mixed for 5 to 8 minutes and vibrated and pressed into shape. The bricks are dried at 100 to 120°C for 24 to 48 hours and sintered at 1450 to 1550°C for 4 to 6 hours to obtain corundum mullite lightweight bricks. However, this patent does not try to recycle useful resources, but instead removes the carbon in the aluminum carbon solid waste by high-temperature burnout, wasting precious graphite carbon resources, and the prepared lightweight bricks rely on the large number of micropores left by the burned carbon to increase the porosity and reduce the thermal conductivity. However, the remaining pores of this burnout method are through-open pores, which lead to convective heat transfer, which is not as effective as closed pores in reducing thermal conductivity, and the through-pores of the burnout method have an extremely negative impact on the strength of lightweight bricks, resulting in low strength of the prepared lightweight bricks. In order to fully utilize the resource efficiency of aluminum carbon solid waste such as skateboards, and further reduce thermal conductivity and improve strength, the present invention has developed a foaming method for preparing corundum-mullite high-strength lightweight bricks. Summary of the invention

[0004] The invention adopts recycled powder of waste skateboards with alumina-carbon as the main component, adds activated alumina powder, corundum fiber, metal aluminum, metal silicon / silicon aluminum alloy powder, uses a composite gelling agent as a binder, adds a foaming agent, a foam stabilizer, and a foam fixing agent, and obtains a lightweight brick blank through stirring and pouring, and then obtains a high-strength lightweight brick that can be used at a temperature above 1450°C and a maximum service temperature of 1600°C through drying and firing.

[0005] The corundum-mullite high-strength lightweight brick of the present invention has the following raw material ratios in parts by mass:

[0006] (1) 40-60 parts of recycled skateboard powder;

[0007] (2) 5 to 15 parts of activated alumina powder;

[0008] (3) corundum fiber, 3-5 parts;

[0009] (4) Aluminum powder, 2 to 4 parts;

[0010] (5) Silicon aluminum alloy powder, 1 to 3 parts;

[0011] (6) composite gelling agent, 10 to 15 parts;

[0012] (7) Foaming agent, 2 to 4 parts;

[0013] (8) Foam stabilizer, 0.5-1 part;

[0014] (9) Foam fixer, 0.1-0.3 parts;

[0015] (10) Water, 30-40 parts.

[0016] Furthermore, the waste skateboard recycled powder is obtained by removing iron and impurities, crushing and screening the used waste skateboard. The particle size of the waste skateboard recycled powder is 0.147-0.044 mm, and the main component content is Al 2 O 3 ≥80%、ZrO 2 ≥3%、SiO 2 ≥10%, C≥5%;

[0017] The particle size of the activated alumina powder is 0.147-0.044 mm;

[0018] The corundum fiber has a diameter of 3 to 5 μm and a length of 3 to 15 mm;

[0019] The particle size of the metal aluminum powder is 0.147-0.044 mm;

[0020] The particle size of the silicon aluminum alloy powder is 0.147-0.044 mm;

[0021] The composite gelling agent is a mixture of alumina sol and aluminum carbonate, and the mixing mass ratio of alumina sol and aluminum carbonate is 10 to 30:1;

[0022] The foaming agent is one or a mixture of cocamidopropyl hydroxysulfonate betaine and dodecyl dimethyl betaine;

[0023] The foam stabilizer is a mixture of acrylic acid ester copolymer and dextrin powder, and the mixing mass ratio of acrylic acid ester copolymer and dextrin powder is 2-3:1;

[0024] The foaming agent is a mixture of aluminum dihydrogen phosphate and magnesia, and the mixing mass ratio of aluminum dihydrogen phosphate to magnesia is 5 to 10:1;

[0025] The preparation process of the above-mentioned corundum-mullite high-strength lightweight brick is as follows: after the recycled material powder of waste skateboard, activated alumina powder, corundum fiber, metal aluminum powder and silicon aluminum alloy powder are mixed evenly, the mixture is placed in a high-speed mixer; a composite gelling agent, water, a foaming agent, a foam stabilizer and a foam fixing agent are added, and the mixture is stirred at high speed for 5 to 15 minutes to obtain a uniform slurry; the slurry is poured into a mold for forming; the slurry is demoulded after curing at room temperature for 0.5 to 2 hours; the slurry is dried, and then sintered in a reducing atmosphere at 1300 to 1400° C. for 5 to 8 hours to obtain the corundum-mullite high-strength lightweight brick of the present invention.

[0026] Beneficial effects of the present invention:

[0027] (1) The recycling process is simple, and there is no need for thorough hydration and baking treatment in the yard. It can absorb a large amount of waste recycling skateboards and is highly economical and practical;

[0028] (2) The prepared lightweight bricks have high strength, and the compressive strength is ≥20MPa when the volume density is ≥1.3g / cm3;

[0029] (3) The prepared lightweight bricks have wide applicability and can be used in high-temperature industrial kilns, energy conservation and environmental protection and other fields. The service temperature can be above 1450°C and the maximum service temperature is 1600°C.

[0030] The present invention utilizes Al generated from the waste slide 4 C 3 and Al 2 O 3 When the lightweight brick is fired, a solid solution reaction occurs, and Al 4 C 3 (s)+4Al 2 O 3 (s)=3Al 4 O 4 C(s), in-situ formation of columnar Al 4 O 4 C interspersed with Al 2 O 3 Bridges are formed between the bricks to achieve toughening and strengthening, thereby improving the mechanical properties of lightweight bricks.

[0031] Al 4 O 4 CAl in an oxidizing environment during service 4 O 4 C(s)+O2 (g) = 2Al 2 O 3 (s) + C (s), or in a local reducing atmosphere the reaction formula is Al 4 O 4 C(s)+2CO(g)=2Al 2 O 3 (s)+3C(s), finally Al 4 O 4 C is consumed and converted into Al 2 O 3 and C, which are further oxidized into highly active Al after long-term service. 2 O 3 , through the pre-added silicon aluminum alloy powder, the Si in the alloy is directly oxidized to produce gaseous SiO, which produces SiC fiber reinforcement and improves the strength of lightweight bricks. When it is oxidized during long-term service, SiO 2 With Al 2 O 3 Further reaction generates mullite reinforcement.

[0032] The recycled powder of waste skateboards of the present invention is mainly composed of alumina, and the gelling agent is not calcium silicate cement or calcium aluminate cement which is not resistant to high temperature, but can be converted into alumina sol at high temperature, so the service temperature is high. The added silicon powder or aluminum silicon alloy powder has an antioxidant protection effect on carbon, and at the same time, promotes the production of SiC whiskers in the firing process of lightweight bricks to strengthen Al 4 O 4 The corundum-mullite lightweight brick combined with C has high strength and good corrosion resistance. The carbon is oxidized into gas and has pore-forming function. The present invention is converted into corundum-mullite lightweight brick after a period of service. Compared with the prior art CN109133880A, which oxidizes and burns away carbon during preparation to make corundum-mullite lightweight brick, the extra carbon is converted into Al 4 O 4 C and SiC whiskers, Al after service 4 O 4 C to Al 2 O 3 , and finally transformed into mullite through several service processes, thus increasing the service life of lightweight bricks, making them stronger and having lower thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The bridging Al in the high-strength lightweight brick of Example 1 4 O 4 C columnar morphology SEM image and EDS spectrum of point 1;

[0034] Figure 2 This is the SEM image of the SiC whisker morphology in the high-strength lightweight brick of Example 1;

[0035] Figure 3 This is an SEM image of the high-strength lightweight brick of Example 1 that has been converted into short-grained mullite after serving at 1500°C for one year. DETAILED DESCRIPTION

[0036] Example 1

[0037] The corundum-mullite high-strength lightweight brick of the present invention has the following raw material ratios in parts by mass:

[0038] (1) Waste skateboard recycled material powder, 40 parts;

[0039] (2) activated alumina powder, 15 parts;

[0040] (3) corundum fiber, 3 parts;

[0041] (4) Aluminum powder, 4 parts;

[0042] (5) Metal silicon aluminum alloy powder, 1 part;

[0043] (6) composite gelling agent, 15 parts;

[0044] (7) foaming agent, 2 parts;

[0045] (8) foam stabilizer, 0.5 part;

[0046] (9) Foam fixer, 0.3 part;

[0047] (10) Water, 30 parts.

[0048] Furthermore, the waste skateboard recycled powder is obtained by removing iron and impurities, crushing and screening the used waste skateboard. The particle size of the waste skateboard recycled powder is 0.147-0.044 mm, and the main component content is Al 2 O 3 ≥80%, ZrO2≥3%, SiO2≥10%, C≥5%;

[0049] The particle size of the activated alumina powder is 0.147-0.044 mm;

[0050] The corundum fiber has a diameter of 3 to 5 μm and a length of 3 to 15 mm;

[0051] The particle size of the metal aluminum powder is 0.147-0.044 mm;

[0052] The particle size of the silicon aluminum alloy powder is 0.147-0.044 mm;

[0053] The composite gelling agent is a mixture of alumina sol and aluminum carbonate, and the mixing mass ratio of alumina sol and aluminum carbonate is 30:1;

[0054] The foaming agent is cocamidopropyl hydroxysulfonate betaine;

[0055] The foam stabilizer is a mixture of acrylic acid ester copolymer and dextrin powder, and the mixing mass ratio of acrylic acid ester copolymer and dextrin powder is 3:1;

[0056] The foaming agent is a mixture of aluminum dihydrogen phosphate and magnesia, and the mixing mass ratio of aluminum dihydrogen phosphate to magnesia is 10:1;

[0057] The preparation process is as follows: after mixing the recycled powder of waste skateboards, activated alumina powder, corundum fiber, metal aluminum powder and silicon aluminum alloy powder evenly, place them in a high-speed mixer; add composite gelling agent, water, foaming agent, foam stabilizer and foam fixing agent, stir at high speed for 5 minutes to obtain uniform mud; pour the mud into a mold to form it; demold after curing at room temperature for 0.5 hours; dry, and then sinter at 1300°C in a reducing atmosphere for 8 hours.

[0058] The bulk density of the lightweight brick prepared in Example 1 is 1.30 g / cm 3 , the room temperature compressive strength is 23MPa, suitable for high temperature industrial kilns, energy conservation and environmental protection and other fields, the service temperature can be above 1450℃, and the maximum service temperature is 1600℃.

[0059] Example 2

[0060] The corundum-mullite high-strength lightweight brick of the present invention has the following raw material ratios in parts by mass:

[0061] (1) 60 parts of recycled skateboard powder;

[0062] (2) 5 parts of activated alumina powder;

[0063] (3) corundum fiber, 5 parts;

[0064] (4) Aluminum powder, 2 parts;

[0065] (5) Metal silicon aluminum alloy powder, 1 part;

[0066] (6) composite gelling agent, 10 parts;

[0067] (7) foaming agent, 4 parts;

[0068] (8) Foam stabilizer, 1 part;

[0069] (9) Foam fixative, 0.1 part;

[0070] (10) Water, 40 parts.

[0071] Furthermore, the waste skateboard recycled powder is obtained by removing iron and impurities, crushing and screening the used waste skateboard. The particle size of the waste skateboard recycled powder is 0.147-0.044 mm, and the main component content is Al 2 O 3 ≥80%、ZrO 2 ≥3%、SiO 2 ≥10%, C≥5%;

[0072] The particle size of the activated alumina powder is 0.147-0.044 mm;

[0073] The corundum fiber has a diameter of 3 to 5 μm and a length of 3 to 15 mm;

[0074] The particle size of the metal aluminum powder is 0.147-0.044 mm;

[0075] The particle size of the silicon aluminum alloy powder is 0.147-0.044 mm;

[0076] The composite gelling agent is a mixture of alumina sol and aluminum carbonate, and the mixing mass ratio of alumina sol and aluminum carbonate is 10:1;

[0077] The foaming agent is dodecyl dimethyl betaine;

[0078] The foam stabilizer is a mixture of acrylic acid ester copolymer and dextrin powder, and the mixing mass ratio of acrylic acid ester copolymer and dextrin powder is 2:1;

[0079] The foaming agent is a mixture of aluminum dihydrogen phosphate and magnesia, and the mixing mass ratio of aluminum dihydrogen phosphate to magnesia is 5:1;

[0080] The preparation process is as follows: after mixing the recycled powder of waste skateboards, activated alumina powder, corundum fiber, metal aluminum powder and silicon aluminum alloy powder evenly, place them in a high-speed mixer; add composite gelling agent, water, foaming agent, foam stabilizer and foam fixing agent, stir at high speed for 15 minutes to obtain uniform mud; pour the mud into a mold to form it; demold after curing at room temperature for 2 hours; dry, and then sinter at 1350°C in a reducing atmosphere for 5 hours.

[0081] The bulk density of the lightweight brick prepared in Example 2 is 1.28 g / cm 3 , the room temperature compressive strength is 21MPa, suitable for high temperature industrial kilns, energy conservation and environmental protection and other fields, the service temperature can be above 1450℃, and the maximum service temperature is 1600℃.

[0082] Example 3

[0083] The corundum-mullite high-strength lightweight brick of the present invention has the following raw material ratios in parts by mass:

[0084] (1) Waste skateboard recycling powder, 50 parts;

[0085] (2) activated alumina powder, 10 parts;

[0086] (3) corundum fiber, 4 parts;

[0087] (4) Aluminum powder, 3 parts;

[0088] (5) Metallic silicon powder, 2 points;

[0089] (6) composite gelling agent, 12 parts;

[0090] (7) foaming agent, 3 parts;

[0091] (8) foam stabilizer, 0.8 part;

[0092] (9) Foam fixer, 0.2 part;

[0093] (10) Water, 35 parts.

[0094] Furthermore, the waste skateboard recycled powder is obtained by removing iron and impurities, crushing and screening the used waste skateboard. The particle size of the waste skateboard recycled powder is 0.147-0.044 mm, and the main component content is Al 2 O 3 ≥80%、ZrO 2 ≥3%, SiO 2 ≥10%, C≥5%;

[0095] The particle size of the activated alumina powder is 0.147-0.044 mm;

[0096] The corundum fiber has a diameter of 3 to 5 μm and a length of 3 to 15 mm;

[0097] The particle size of the metal aluminum powder is 0.147-0.044 mm;

[0098] The particle size of the silicon aluminum alloy powder is 0.147-0.044 mm;

[0099] The composite gelling agent is a mixture of alumina sol and aluminum carbonate, and the mixing mass ratio of alumina sol and aluminum carbonate is 20:1;

[0100] The foaming agent is a mixture of cocamidopropyl hydroxysulfonic acid betaine and dodecyl dimethyl betaine of equal mass;

[0101] The foam stabilizer is a mixture of acrylic acid ester copolymer and dextrin powder, and the mixing mass ratio of acrylic acid ester copolymer and dextrin powder is 2:1;

[0102] The foaming agent is a mixture of aluminum dihydrogen phosphate and magnesia sand, and the mixing mass ratio of aluminum dihydrogen phosphate to magnesia sand is 5:1.

[0103] The preparation process is as follows: after mixing the recycled powder of waste skateboards, activated alumina powder, corundum fiber, metal aluminum powder and silicon aluminum alloy powder evenly, place them in a high-speed mixer; add composite gelling agent, water, foaming agent, foam stabilizer and foam fixing agent, stir at high speed for 10 minutes to obtain uniform mud; pour the mud into a mold to form it; demold after curing at room temperature for 1 hour; dry, and then sinter at 1400°C in a reducing atmosphere for 7 hours.

[0104] The bulk density of the lightweight brick prepared in Example 3 is 1.29 g / cm 3 , the room temperature compressive strength is 22MPa, suitable for high temperature industrial kilns, energy conservation and environmental protection and other fields, the service temperature can be above 1450℃, and the maximum service temperature is 1600℃.

Claims

1. A corundum-mullite high-strength lightweight brick, the raw material ratio is calculated by mass: (1) 40-60 parts of recycled skateboard powder; (2) 5 to 15 parts of activated alumina powder; (3) corundum fiber, 3-5 parts; (4) Aluminum powder, 2 to 4 parts; (5) Silicon aluminum alloy powder, 1 to 3 parts; (6) composite gelling agent, 10 to 15 parts; (7) Foaming agent, 2 to 4 parts; (8) Foam stabilizer, 0.5-1 part; (9) Foam fixer, 0.1-0.3 parts; (10) Water, 30-40 parts. The waste skateboard recycled powder is obtained by removing iron and impurities, crushing and screening the used waste skateboard. The particle size of the waste skateboard recycled powder is 0.147-0.044mm, and the main components are Al2O3≥80%, ZrO2≥3%, SiO2≥10%, and C≥5%.

2. The lightweight brick according to claim 1, characterized in that: The particle size of the activated alumina powder is 0.147-0.044 mm.

3. The lightweight brick according to claim 1, characterized in that: The corundum fiber has a diameter of 3 to 5 μm and a length of 3 to 15 mm.

4. The lightweight brick according to claim 1, characterized in that: The particle size of the metal aluminum powder is 0.147-0.044 mm.

5. The lightweight brick according to claim 1, characterized in that: The particle size of the silicon aluminum alloy powder is 0.147-0.044 mm.

6. The lightweight brick according to claim 1, characterized in that: The composite gelling agent is a mixture of alumina sol and aluminum carbonate, and the mixing mass ratio of alumina sol to aluminum carbonate is 10-30:

1.

7. The lightweight brick according to claim 1, characterized in that: The foaming agent is one or a mixture of cocamidopropyl hydroxysulfonic acid betaine and dodecyl dimethyl betaine.

8. The lightweight brick according to claim 1, characterized in that: The foam stabilizer is a mixture of acrylic acid ester copolymer and dextrin powder, and the mixing mass ratio of the acrylic acid ester copolymer and the dextrin powder is 2-3:

1.

9. The lightweight brick according to claim 1, characterized in that: The foaming agent is a mixture of aluminum dihydrogen phosphate and magnesia sand, and the mixing mass ratio of aluminum dihydrogen phosphate to magnesia sand is 5-10:

1.

10. The preparation process of the corundum-mullite high-strength lightweight brick according to claims 1 to 9, characterized in that: The waste skateboard recycled material powder, activated alumina powder, corundum fiber, metal aluminum powder and silicon aluminum alloy powder are mixed evenly according to the proportion, and placed in a high-speed mixer; composite gelling agent, water, foaming agent, foam stabilizer and foam fixing agent are added, and stirred at high speed for 5 to 15 minutes to obtain uniform mud; the mud is poured into a mold for molding; after curing at room temperature for 0.5 to 2 hours, the mold is demoulded; dried, and then sintered at 1300 to 1400°C in a reducing atmosphere for 5 to 8 hours.

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