Mullite high-temperature hot patching material

Abstract

The mullite high-temperature hot patching material is prepared by mixing the electro-fused mullite, the bimodal alumina micro powder, the additive modified powder, the electro-fused mullite, the fast sintering agent, the clay, the coagulant and the sintering aid, carrying out hot-state patching construction operation by adopting an injection machine or a spray gun, and carrying out fast reaction and sintering in a hot state to obtain a compact refractory material. The refractoriness of the generated refractory material is greater than or equal to 1750 DEG C, the load softening point is greater than or equal to 1700 DEG C, and the refractory material can bear 1700 DEG C high-temperature

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology of inorganic non-metallic materials, and specifically relates to a mullite high-temperature heat-repairing material. Background Technology

[0002] High-temperature incineration is an important method for hazardous waste treatment. Compared with other technologies, high-temperature incineration technology has significant advantages in the thoroughness of hazardous component treatment, the reduction of effluent (80wt% / 95vol%), and its adaptability to various complex organic compounds. Hazardous waste incineration equipment includes two combustion chambers: a primary combustion chamber and a secondary combustion chamber. The primary combustion chamber vaporizes, decomposes, and burns most organic matter, while the secondary combustion chamber oxidizes and incinerates all organic matter and combustible gases. The primary combustion chamber performs pyrolysis and preliminary combustion, while the secondary combustion chamber performs deep combustion to achieve complete incineration. The furnace lining of the incinerator is in long-term contact with molten slag. Not only do components such as Na2O, K2O, CaO, Fe2O3, SiO2, and Cl in the slag readily react with the material to form liquid or expanded phases, leading to premature material damage, but the scouring of the material and slag also accelerates material consumption, resulting in a shorter service life. Meanwhile, the sodium and potassium components in the slag readily react with HCl and HF to generate large amounts of corrosive gaseous NaCl, KCl, NaF, and KF, which deposit and adhere to the furnace lining surface during cooling, accelerating material damage. Incineration corrosion and emission abrasion make the furnace lining prone to damage. After damage, to prevent furnace collapse, it is usually shut down and repaired with new refractory bricks, which disrupts production processes and schedules.

[0003] Hot repair does not require shutting down the furnace and does not affect production. However, hot-temperature repair requires a repair material that can react and sinter quickly, so that the repair material and the original brick can react and bond together quickly. The repair material is fired into a dense brick body with excellent high-temperature strength and corrosion resistance. Summary of the Invention

[0004] This invention relates to a mullite high-temperature heat-repairing material, primarily used in easily damaged areas such as the secondary combustion chamber of hazardous waste incinerators and the combustion chamber of waste liquid and waste gas incinerators. These areas are characterized by high operating temperatures, severe slag intrusion, intense corrosion, and a tendency to flak off. The corundum-mullite high-temperature heat-repairing material of this invention meets the requirements for rapid repair operations. During furnace operation, it reacts quickly to form a dense refractory material, exhibiting high strength, corrosion resistance, and strong resistance to slag intrusion after firing.

[0005] The present invention provides a mullite high-temperature heat-converting material, characterized by its raw material formulation, which, by weight, is as follows: (1) 15-20 parts of fused mullite with a particle size of 5-3 mm; (2) 20-30 parts of fused mullite with a particle size of 3-1 mm; (3) 5-10 parts of bimodal alumina micro powder with a particle size of 3-5 μm; (4) 22-50 parts of additive-modified powder with a particle size of 3-1μm; (5) Fast-burning agent, 5-8 parts; (6) Clay, 1-3 parts; (7) Coagulant, 3-5 parts; (8) Sintering aid, 5-8 parts; The additive modified powder is a mixture of micron-sized lightly calcined magnesium oxide modified powder, mullite micro powder, and magnesium zircon sand fine powder prepared by electrofusion. The ratio of lightly calcined magnesium oxide modified powder: mullite micro powder: magnesium zircon sand fine powder in the mixture is 1:1:1. The rapid-burning agent is a powder mixture of lightly calcined MgO micro powder and silica in a 5:1 ratio. The coagulant is a mixture of silica sol and aluminum dihydrogen phosphate in a 3:1 ratio; The sintering aid is a mixture of kaolin and sodium silicate in an 8:1 ratio.

[0006] During construction, a spraying machine or spray gun is used. The refractory material gains sufficient velocity within the pipe using compressed air or mechanical pressure, and is sprayed onto the surface to be sprayed, thus forming a strong coating. These raw materials are mixed according to the instructions and added to the spraying machine. When working on a damaged furnace heating element, the spraying machine is used to apply the coating to the damaged area, resulting in a rapid reaction at high temperatures. The mullite high-temperature heat repair material of this invention undergoes a series of chemical reactions during high-temperature heat repair.

[0007] When water is added for spraying, MgO micro powder and silica react rapidly to produce a high-melting-point network of MgO-SiO2-H2O sol. This facilitates the improvement of the initial strength of the quick-fix material, and the high-temperature hot-fixing effect is significant, which facilitates the rapid sintering of the repair material. The resulting repair volume ensures a dense bond between the repair material and the original brick body.

[0008] The coagulant of this invention is a mixture of silica sol and aluminum dihydrogen phosphate in a specific ratio. Silica sol exhibits high dispersibility, and the addition of SiO2 nanoparticles in liquid form allows for uniform dispersion within the refractory material, improving its stability and uniformity. Nano-SiO2 also possesses advantages such as high reactivity and high bonding efficiency. Furthermore, the silica sol has low viscosity, allowing it to effectively fill gaps within the material. After drying, it forms a continuous gel structure, resulting in good cured strength. Adding certain metal ions to the silica sol can form new chemical bonds, Si-OM (metal), which offer advantages in bond strength and formation time compared to siloxane bonds, thus contributing to improved material strength. Additionally, since the silica sol does not contain low-melting-point components, the samples prepared using this binder exhibit good high-temperature performance and can be used in high-temperature environments; aluminum dihydrogen phosphate [Al(H2PO4)3] is water-soluble at room temperature. Due to its high viscosity, strong room-temperature curing ability, good high-temperature resistance, and low price, the aluminum dihydrogen phosphate-bonded spraying material of this invention can achieve high strength after drying at room temperature for a period of time. Adding MgO and other substances to induce a dehydration polymerization reaction can accelerate its room-temperature curing and shorten the curing time. During spraying, aluminum dihydrogen phosphate transforms into aluminum acid phosphate. As the temperature continues to rise, the reaction product transforms into aluminum pyrophosphate, and finally into aluminum metaphosphate. When the temperature continues to rise, aluminum metaphosphate undergoes a polymerization reaction to form aluminum metaphosphate polymers. Some of the aluminum metaphosphate polymers also decompose into P2O5 and AlPO4. P2O5 reacts with Al2O3 inside the refractory material to form AlPO4, and the formation of AlPO4 further increases the strength of the refractory material.

[0009] Using fused mullite and additives reduces the content of low-melting-point impurities in the product. This effectively prevents the formation of a liquid phase at high temperatures and reduces slag adhesion and erosion during use. It produces dense refractory bricks with fully developed mullite phases during high-temperature repair and use. Adding these materials significantly improves the coefficient of linear expansion at high temperatures and reduces the product's porosity from approximately 20% to below 10%, thereby minimizing slag intrusion and corrosion.

[0010] Electron microscopy revealed that the hot-filled material formed a dense structure after sintering, such as... Figure 1 The main components, as determined by X-ray diffraction, are mullite, corundum, zirconium oxide, and a small amount of SiO2, such as... Figure 2 .

[0011] After repair and high-temperature service in the furnace, the resulting refractory material has a refractoriness of ≥1750℃ and a load softening point of ≥1700℃, and can withstand long-term high-temperature service at 1700℃. Attached Figure Description

[0012] Figure 1SEM image of a mullite high-temperature hot patching material after hot repair and incineration, Example 1; Figure 2 The X-ray diffraction pattern is shown in Example 1 of a mullite high-temperature heat-filling material. Detailed Implementation Example 1

[0013] A mullite high-temperature heat-mixing material, with the following formula by weight parts: (1) 15 parts of fused mullite with a particle size of 5-3 mm; (2) 20 parts of fused mullite with a particle size of 3-1 mm; (3) 5 parts of bimodal alumina micro powder with a particle size of 3~5μm; (4) 50 parts of additive-modified powder with a particle size of 3~1μm; (5) Rapid-burning agent, 5 parts; (6) Clay, 3 parts; (7) Coagulant, 5 parts; (8) Sintering aid, 5 parts; The additive modified powder is a mixture of micron-sized lightly calcined magnesium oxide modified powder, mullite micro powder, and magnesium zircon sand fine powder prepared by electrofusion. The ratio of lightly calcined magnesium oxide modified powder: mullite micro powder: magnesium zircon sand fine powder in the mixture is 1:1:1. The rapid-burning agent is a powder mixture of lightly calcined MgO micro powder and silica in a 5:1 ratio. The coagulant is a mixture of silica sol and aluminum dihydrogen phosphate in a 3:1 ratio; The sintering aid is a mixture of kaolin and sodium silicate in an 8:1 ratio.

[0014] These raw materials are mixed according to the instructions and added to a spraying machine. While the hot zone of the damaged furnace is operating, the spraying machine is used to apply the adhesive to the damaged area. A series of chemical reactions occur at high temperatures, forming a dense refractory material. The microstructure of Example 1 is shown in the attached SEM image of the instruction manual. An electron microscope reveals a dense micrograph of the hot-pressed material after sintering, with a porosity of 9%. After repair and high-temperature service in the furnace, the resulting refractory material has a refractoriness of 1750℃, a load softening point of 1710℃, and can withstand long-term service at 1700℃. Example 2

[0015] A mullite high-temperature heat-mixing material, with the following formula by weight parts: (1) 20 parts of fused mullite with a particle size of 5-3 mm; (2) 20 parts of fused mullite with a particle size of 3-1 mm; (3) 10 parts of bimodal alumina micro powder with a particle size of 3~5μm; (4) 22 parts of additive-modified powder with a particle size of 3~1μm; (5) Rapid-burning agent, 8 parts; (6) Clay, 1 part; (7) Coagulant, 5 parts; (8) Sintering aid, 8 parts; The additive modified powder is a mixture of micron-sized lightly calcined magnesium oxide modified powder, mullite micro powder, and magnesium zircon sand fine powder prepared by electrofusion. The ratio of lightly calcined magnesium oxide modified powder: mullite micro powder: magnesium zircon sand fine powder in the mixture is 1:1:1. The rapid-burning agent is a powder mixture of lightly calcined MgO micro powder and silica in a 5:1 ratio. The coagulant is a mixture of silica sol and aluminum dihydrogen phosphate in a 3:1 ratio; The sintering aid is a mixture of kaolin and sodium silicate in an 8:1 ratio.

[0016] These raw materials are mixed according to the formula and added to a spraying machine. While working on the damaged furnace heating element, the spraying machine is used to apply the adhesive to the damaged area. A series of chemical reactions occur at high temperatures, forming a dense refractory material with a porosity of 9.5%. After repair and high-temperature service in the furnace, the resulting refractory material has a refractoriness of 1760℃, a load softening point of 1710℃, and can withstand long-term high-temperature service at 1700℃. Example 3

[0017] A mullite high-temperature heat-mixing material, with the following formula by weight parts: (1) 17 parts of fused mullite with a particle size of 5-3 mm; (2) 25 parts of fused mullite with a particle size of 3-1 mm; (3) 7 parts of bimodal alumina micro powder with a particle size of 3~5μm; (4) 35 parts of additive-modified powder with a particle size of 3~1μm; (5) Rapid-burning agent, 6 parts; (6) Clay, 2 parts; (7) Coagulant, 4 parts; (8) Sintering aid, 6 parts; The additive modified powder is a mixture of micron-sized lightly calcined magnesium oxide modified powder, mullite micro powder, and magnesium zircon sand fine powder prepared by electrofusion. The ratio of lightly calcined magnesium oxide modified powder: mullite micro powder: magnesium zircon sand fine powder in the mixture is 1:1:1. The rapid-burning agent is a powder mixture of lightly calcined MgO micro powder and silica in a 5:1 ratio. The coagulant is a mixture of silica sol and aluminum dihydrogen phosphate in a 3:1 ratio; The sintering aid is a mixture of kaolin and sodium silicate in an 8:1 ratio.

[0018] These raw materials are mixed according to the formula and added to a spraying machine. While working on the damaged furnace heating element, the spraying machine is used to apply the adhesive to the damaged area. A series of chemical reactions occur at high temperatures, forming a dense refractory material with a porosity of 9.6%. After repair and high-temperature service in the furnace, the resulting refractory material has a refractoriness of 1750℃, a load softening point of 1710℃, and can withstand long-term service at temperatures up to 1700℃.

Claims

1. A mullite high temperature hot mix, characterized technically in that Raw material formula, by weight, the formula is: (1) 15~20 parts of fused mullite with particle size of 5~3mm; (2) 20~30 parts of fused mullite with particle size of 3~1mm; (3) 5~10 parts of bimodal alumina micropowder with particle size of 3~5μm; (4) 22~50 parts of additive modified powder with particle size of 3~1μm; (5) 5~8 parts of fast burning agent; (6) 1~3 parts of clay; (7) 3~5 parts of condensing agent; (8) 5~8 parts of sintering aid; The additive modified powder is a mixture of micron grade light-burned magnesium oxide modified powder, mullite micropowder and self-fused prepared magnesium-zirconium sand fine powder, and the ratio of light-burned magnesium oxide modified powder, mullite micropowder and magnesium-zirconium sand fine powder in the mixture is 1:1:1; The fast burning agent is a mixed powder of light-burned MgO micropowder and white carbon black with a ratio of 5:1; The condensing agent is a mixed sol of silica sol and aluminum dihydrogen phosphate with a ratio of 3:1; The sintering aid is a mixture of kaolin and sodium silicate with a ratio of 8:

1.

2. During construction, a sprayer or a spray gun is used for hot-state repair construction operation, the raw materials are mixed according to the formula, added into the sprayer, and the sprayer is used to spray and adhere to the damaged position while the damaged furnace is working in a high temperature zone, so that the fast response is realized under high temperature.

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