A channel gunning mix prepared from main channel waste

Abstract

The application provides a slag channel gunning material prepared from main channel waste, which comprises the following components in parts by weight: main channel waste 45-62 parts, brown corundum 12-20 parts, silicon carbide 10-15 parts, calcium aluminate cement 2-4 parts, alumina micropowder 4-8 parts, spherical pitch 2-5 parts, silicon micropowder 0.9-1.5 parts, aluminum powder 0.02-0.08 parts, organic fiber 0.04-0.08 parts, functional additive 1.3-1.7 parts, and rare earth core-shell aggregate 5-10 parts. The main channel waste is changed from waste to treasure by adding the rare earth core-shell aggregate and the regulation of the matrix powder, and the prepared slag channel gunning material has the characteristics of good heat insulation performance, strong bonding force with a working layer and excellent resistance to slag erosion. In addition, the slag channel gunning material has simple construction, low cost and excellent performance.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and in particular relates to a slag trench spraying material prepared using waste material from the main trench. Background Technology

[0002] Due to the erosion caused by the slag-iron mixture, the lining of the blast furnace tapping trough often needs to be replaced frequently. However, the replaced lining usually has no other use and is directly discarded, resulting in a waste of resources.

[0003] Currently, most steel companies use the same castable refractory as the main ditch as the lining material to ensure the service life of the slag trench, which increases the cost of slag trench preparation and causes unnecessary waste of resources. Based on these issues, it is necessary to develop a slag trench spraying material prepared using waste from the main ditch. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and propose a slag trench spraying material prepared using waste material from the main trench.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: In a first aspect, the present invention provides a slag trench spraying material prepared from main trench waste, in a total quantity of 100 parts, comprising the following components in parts by weight: Main ditch waste 45-62 parts, brown corundum 12-20 parts, silicon carbide 10-15 parts, calcium aluminate cement 2-4 parts, alumina powder 4-8 parts, spherical asphalt 2-5 parts, silica powder 0.9-1.5 parts, metallic aluminum powder 0.02-0.08 parts, organic fiber 0.04-0.08 parts, functional additives 1.3-1.7 parts, rare earth core-shell aggregate 5-10 parts.

[0006] Preferably, the main ditch waste undergoes the following screening process: main ditch waste with slag and iron adhering to it is selected out, the remaining main ditch waste is crushed, the crushed main ditch waste is subjected to magnetic separation to remove iron, and then the main ditch waste is placed into a grading screen for screening, and the crushed main ditch waste is divided into aggregates with a particle size of less than or equal to 8 mm and greater than 5 mm, a particle size of less than or equal to 5 mm and greater than 3 mm, a particle size of less than or equal to 3 mm and greater than 1 mm, and a particle size of less than or equal to 1 mm and greater than 0, and the weight parts added are 11-16 parts, 14-17 parts, 12-15 parts, and 8-14 parts respectively.

[0007] Preferably, the alumina content in the brown fused alumina is ≥90 wt%; wherein, the weight parts of brown fused alumina with a particle size of less than or equal to 15 mm and greater than 8 mm are 7-12 parts, and the weight parts of brown fused alumina with a particle size of 45 μm are 5-8 parts.

[0008] Preferably, the silicon carbide contains ≥97 wt% SiC and has a particle size ≤45 μm.

[0009] Preferably, the spherical asphalt contains 55 wt% fixed carbon and has a softening point of 119°C.

[0010] Preferably, the calcium aluminate cement has an Al2O3 content of ≥70wt% and a particle size of <45μm.

[0011] Preferably, the alumina micro powder contains ≥98 wt% α-Al2O3 and has a particle size ≤6.5 μm.

[0012] Preferably, the silicon micropowder has a SiO2 content ≥ 94 wt% and a particle size ≤ 0.5 μm.

[0013] Preferably, the aluminum powder contains ≥99 wt% Al and has a particle size ≤0.5 μm.

[0014] Preferably, the organic fiber is a polypropylene fiber with a length of 3-5 mm and a diameter of 40 μm.

[0015] Preferably, the functional additives include lithium carbonate and boron carbide in a mass ratio of 1:(1-3) and a particle size ≤0.074mm.

[0016] Preferably, the method for preparing rare earth core-shell aggregate includes the following steps: S1: Lanthanum phosphate and boron oxide were ball-milled and blended until D90≤3μm, then vacuum dried, and then pulverized and sieved to obtain a mixture of lanthanum phosphate and cerium oxide. S2: Add polyvinyl alcohol to the obtained lanthanum phosphate and cerium phosphate mixture, mix thoroughly, and then cold isostatically press under a pressure of 100-150 MPa for 20-40 min. After pressing, let stand at room temperature for 24-36 h, and then perform temperature-raising sintering. The gradient sintering process is as follows: First stage: Heat to 600℃ at a heating rate of 2-3℃ / min, and hold for 1-2 hours; Second stage: Heat to 1650-1700℃ at a heating rate of 4-6℃ / min, hold for 7-10h, and then sinter and densify under normal pressure. The third stage: the furnace temperature is reduced to room temperature at a rate of 2℃ / min; the furnace temperature is slowly reduced to room temperature to avoid stress protrusion caused by too rapid a cooling rate, which could lead to material cracking. S3: The sintered material is crushed into granules with a particle size of 1-3mm. The granules are immersed in an aluminum sol solution and then left to stand for 1-5 hours. The granules are then poured into a mixed powder of Al2O3 and SiO2, stirred, and left to stand for 20-24 hours. Finally, the temperature is raised to 1450-1500℃ at a heating rate of 4-7℃ / min and held for 5-7 hours to form a dense mullite shell on the surface of the granules, thus obtaining rare earth core-shell aggregate.

[0017] Preferably, in step S1, the mass ratio of boron oxide to lanthanum cerium phosphate is 1%-4%.

[0018] Preferably, the mass ratio of Al2O3 to SiO2 in the mixed powder in step S3 is (17-19):(6-8).

[0019] More preferably, in step S1, the mass ratio of material, balls, and deionized water during ball milling is 1:(1-3):(0.8-1.2), and the ball milling is carried out at a speed of 270-330 r / min. After ball milling until D90≤3μm, the mixture is vacuum dried at 60-80℃. After drying, the mixture is pulverized and sieved to obtain a lanthanum and cerium phosphate mixture (passed through a 25μm nylon sieve to break up soft agglomerates).

[0020] More preferably, the amount of polyvinyl alcohol added in step S2 is 1%-3% of the total mass of the lanthanum phosphate and cerium phosphate mixture.

[0021] More preferably, in step S3, the granules are immersed in an aluminum sol solution with a mass percentage of 10%-20% for 20-40 minutes, and then evenly spread on a screen and left to stand for 1-5 hours as an adhesive layer.

[0022] Secondly, the present invention also provides a construction method for the above-mentioned slag trench spraying material, comprising the following steps: mixing the main trench waste, brown corundum, silicon carbide, calcium aluminate cement, alumina micro powder, spherical asphalt, silica micro powder, metallic aluminum powder, organic fiber, functional additives, and rare earth core-shell aggregate evenly to obtain powder, then adding water accounting for 4%-8% of the total mass of the powder, mixing and stirring to form a slurry, and pumping the slurry through a conveying pipeline to the nozzle of the spraying machine, and then using high-pressure air to spray the mixed slurry onto the damaged surface of the slag trench that needs to be repaired through the nozzle.

[0023] Rare earth core-shell aggregates, using rare earth phosphate as the core and mullite as the outer shell, are introduced into the sprayed refractories to achieve a gradient erosion resistance mechanism in the refractory material. The mullite shell initially contacts the eroding slag, providing physical barrier and initial resistance due to its high melting point and high strength. When the mullite shell is eroded through under long-term extreme conditions, the exposed lanthanum-cerium phosphate core exhibits strong chemical inertness to the slag, becoming an excellent chemical barrier that greatly delays the further penetration of the eroding slag into the material's interior, thereby extending the service life of the refractory material.

[0024] In addition, lanthanum phosphate has a monazite structure with large cell volume and irregular atomic arrangement. The structure exhibits lattice distortion, which enhances phonon scattering. Therefore, lanthanum phosphate has a low thermal conductivity, which improves the thermal insulation performance of the slag trench material, effectively preventing the temperature of the working layer from being conducted into the interior of the sprayed material, and preventing the further diffusion of slag and iron adhering to the damaged area.

[0025] Boron oxide itself has a melting point of approximately 450℃. During the heating process, it reacts with lanthanum phosphate to form a low-melting-point liquid phase of rare-earth borate. This significantly reduces the sintering temperature of lanthanum phosphate and cerium phosphate, minimizing phosphorus volatilization and cerium valence state changes. During sintering, the liquid phase is uniformly dispersed at the grain boundaries, acting as a pinning agent and restricting rapid grain migration, thereby obtaining fine and uniform grains and promoting a denser lanthanum phosphate core-shell aggregate.

[0026] The formula uses alumina micro powder, silica micro powder, and pure calcium aluminate cement as composite binders. Pure calcium aluminate cement provides initial bonding strength and can withstand high vapor pressure, thus preventing cracking. When the temperature is between 800-1100℃, the amorphous SiO2 in the silica micro powder begins to flow viscously, further promoting interparticle closure and densification, providing medium-temperature strength. When the temperature is above 1300℃, the reaction between Al2O3 and SiO2 accelerates, generating a large amount of mullite, which forms a strong bonding phase with corundum aggregate, significantly improving the high-temperature strength and erosion resistance of the material.

[0027] The functional additives selected are B4C and Li2CO3. B4C begins to react at medium to high temperatures (>800℃), cleaning the interface and generating a B2O3 liquid phase; Li2CO3 decomposes at medium to low temperatures (>720℃) to form active Li2O. The resulting Li2O-B2O3-Al2O3-SiO2 multi-component liquid phase system maintains high activity within a temperature range of 900℃-1400℃. In the interfacial region, the liquid phase facilitates the formation of the aluminosilicate phase. These new phases act like "rivets" to connect the new and old materials, helping the patching material to bond strongly with the existing groove material at lower temperatures.

[0028] Compared with the prior art, the present invention has the following advantages: This invention, through the addition of rare earth core-shell aggregate and matrix powder, transforms main trench waste into a valuable resource. The resulting slag trench spraying material exhibits excellent thermal insulation, strong adhesion to the working layer, and superior resistance to molten slag erosion. Furthermore, this slag trench spraying material is simple to apply, low in cost, and boasts superior performance. Attached Figure Description

[0029] Figure 1 This is an electron microscope image of the surface microstructure of the rare earth core-shell aggregate obtained in Example 1 of the present invention. Figure 2This is an electron microscope image of the contact area between the sprayed material and the molten slag described in Embodiment 2 of the present invention. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In this document, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0032] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0033] In this article, the terms "multiple" or "more than" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0034] In this document, the terms "preferred" and "more preferred" are used only to describe implementation methods or embodiments with better effects, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0035] In this document, terms such as "further" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0036] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0037] In this document, the term "about" means a specified value of + / - 10%, preferably + / - 5%, and more preferably + / - 1%.

[0038] In this article, the terms “include,” “including,” “have,” “contain,” etc., are all open-ended terms, meaning that they include but are not limited to.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0040] In the following examples and comparative examples: the alumina content in brown fused alumina is ≥90wt%; the Al2O3 content in calcium aluminate cement is ≥70wt% with a particle size <45μm; the α-Al2O3 content in alumina micro powder is ≥98wt% with a particle size ≤6.5μm; the SiO2 content in silica micro powder is ≥94wt% with a particle size ≤0.5μm; the aluminum content in metallic aluminum powder is ≥99wt% with a particle size ≤0.5μm; the organic fiber is polypropylene fiber with a length of 3-5mm and a diameter of 40μm; and the particle size of the functional additive is ≤0.074mm.

[0041] The present invention will be described in detail below with reference to the embodiments.

[0042] Example 1 A slag trench spraying material prepared using main ditch waste, comprising the following components and their respective mass percentages: 50 parts main ditch waste; 12 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 8 parts brown fused alumina with a particle size of 45 μm; 12 parts silicon carbide; 3 parts calcium aluminate cement; 4 parts alumina micro powder; 3 parts spherical asphalt; 1.2 parts silica micro powder; 0.02 parts metallic aluminum powder; 0.08 parts organic fiber; 1.7 parts functional additives; and 5 parts rare earth core-shell aggregate.

[0043] The main ditch waste undergoes the following screening process: waste with slag and iron adhering to it is removed; the remaining waste is crushed; the crushed waste is then subjected to magnetic separation to remove iron; and finally, it is placed in a grading screen for further screening. The crushed waste is divided into aggregates with particle sizes less than or equal to 8 mm and greater than 5 mm, less than or equal to 5 mm and greater than 3 mm, less than or equal to 3 mm and greater than 1 mm, and less than or equal to 1 mm and greater than 0 mm, with a mass ratio of 13:15:12:10. The mass ratio of lithium carbonate to boron carbide in the functional additives is 1:1.

[0044] Preparation process of rare earth core-shell aggregate: S1: Lanthanum phosphate and boron oxide are ball-milled and blended. The mass ratio of boron oxide to lanthanum phosphate is 2%. The mass ratio of the material, zirconium oxide grinding beads and deionized water in the ball mill is 1:1:0.8. The mixture is ball-milled at 270 r / min until D90≤3μm. Then it is vacuum dried at 60℃. After drying, it is pulverized and passed through a 25μm nylon sieve to obtain the lanthanum phosphate and cerium oxide mixture. S2: Add 1 wt% PVA to the obtained lanthanum phosphate and cerium phosphate mixture. After mixing evenly, apply a pressure of 100 MPa using a cold isostatic press and hold for 40 min. After pressing, let stand at room temperature for 24 h, and then sinter at a higher temperature. The gradient sintering regime is as follows: First stage: Increase the temperature to 600℃ at a rate of 2℃ / min and hold for 1 hour; Second stage: Increase the temperature to 1650℃ at 4℃ / min and hold for 10 hours; Third stage: Slowly reduce the furnace temperature to room temperature at a rate of 2℃ / min; S3: The sintered material is crushed into particles with a diameter of 1-3 mm. These particles are immersed in a 10% (w / w) aluminum sol solution for 40 min, then evenly spread on a sieve and left to stand for 1 h as a bonding layer. The standing particles are then poured into a mixture (Al2O3:SiO2 mass ratio 17:8) and stirred at low speed using a mixer to ensure uniform coating on each particle. This mixture is then left to stand for 20 h. Finally, the temperature is increased to 1450℃ at a rate of 4℃ / min and held for 7 h to obtain the rare earth core-shell aggregate. The electron microscope image of the surface microstructure of the obtained rare earth core-shell aggregate is shown below. Figure 1 As shown.

[0045] The above raw materials were poured into a mixer and rotated for 30 minutes. Then, they were dry-mixed in a mixer for 3 minutes. Water accounting for 8% of the raw material mass was added and stirred for another 3 minutes. The mixture was then placed in a mold and vibrated to form the product. The product was cured at room temperature for 24 hours, dried at 110℃ for 24 hours, and sintered at 1450℃ for 3 hours. The thermal conductivity, bulk density, flexural strength, compressive strength, linear change rate, and slag erosion rate were measured. The properties are shown in Table 1.

[0046] Example 2 A slag trench spraying material prepared using main ditch waste, comprising the following components and their respective mass percentages: 55 parts main ditch waste; 8 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 6 parts brown fused alumina with a particle size of 45 μm; 10 parts silicon carbide; 2 parts calcium aluminate cement; 4 parts alumina micro powder; 5 parts spherical asphalt; 1.2 parts silica micro powder; 0.02 parts metallic aluminum powder; 0.08 parts organic fiber; 1.7 parts functional additives; and 7 parts rare earth core-shell aggregate.

[0047] The main ditch waste undergoes the following screening process: waste with slag and iron adhering to it is picked out; the remaining waste is crushed; the crushed waste is then subjected to magnetic separation to remove iron; and finally, it is placed in a grading screen for further screening to separate it into aggregates with particle sizes of ≤8mm and >5mm, ≤5mm and >3mm, ≤3mm and >1mm, and ≤1mm and >0mm, with a mass ratio of 14:16:13:12. The mass ratio of lithium carbonate to boron carbide in the functional additives is 1:2.

[0048] Preparation process of rare earth core-shell aggregate: S1: Lanthanum phosphate and cerium phosphate were ball-milled and blended with boron oxide. The mass ratio of boron oxide to lanthanum phosphate and cerium phosphate was 3%. The mass ratio of the material, zirconium oxide grinding beads and deionized water in the ball mill was 1:2:1. The mixture was ball-milled at a speed of 290 r / min until D90≤3μm. Then it was vacuum dried at 70℃. After drying, it was pulverized and passed through a 25μm nylon sieve to obtain a mixture of lanthanum phosphate and cerium phosphate. S2: Add 2wt% PVA to the obtained lanthanum phosphate and cerium phosphate mixture, mix thoroughly, apply a pressure of 125MPa using a cold isostatic press, hold for 30min, after pressing, let stand at room temperature for 30h, and then sinter by heating. The gradient sintering regime is as follows: First stage: Increase the temperature to 600℃ at a rate of 2.5℃ / min and hold for 1.5 hours; Second stage: Increase the temperature to 1670℃ at a rate of 5℃ / min and hold for 8 hours; Third stage: Slowly reduce the furnace temperature to room temperature at a rate of 2℃ / min; S3: The sintered material is crushed into granules with a particle size of 1-3 mm. The granules are immersed in an aluminum sol solution with a mass percentage of 15% for 30 min. Then, they are evenly spread on a sieve and left to stand for 3 h as a bonding layer. The granules are poured into the mixture (Al2O3 to SiO2 mass ratio of 18:7) and stirred at low speed with a mixer to ensure that each granule is evenly coated. The mixture is then left to stand for 22 h. Finally, the temperature is raised to 1470℃ at a rate of 5℃ / min and held for 6 h to obtain rare earth core-shell aggregate.

[0049] The spraying material of Example 2 was tested as follows: The spraying material was filled into the damaged area of ​​the slag trench. After 60 hours of slag clearance, a portion of the spraying material adhering to the molten slag was removed from this area and prepared as a scanning electron microscope sample. The microstructure was observed as follows: Figure 2 The improved spraying material has a tighter bond between the matrix, recycled aggregate, and rare earth core-shell structure, resulting in a significant increase in density and preventing slag from eroding the spraying material along the pores. At the same time, the introduction of the rare earth core-shell structure can compensate for the insufficient strength of the recycled aggregate and play a gradient anti-erosion role, thereby improving the working cycle of the spraying material.

[0050] The preparation and performance testing of the test blocks were the same as in Example 1, and the performance is shown in Table 1.

[0051] Example 3 A slag trench spraying material prepared using main ditch waste, comprising the following components and their respective mass percentages: 45 parts main ditch waste; 7 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 6 parts brown fused alumina with a particle size of 45 μm; 15 parts silicon carbide; 4 parts calcium aluminate cement; 8 parts alumina micro powder; 2 parts spherical asphalt; 1.5 parts silica micro powder; 0.06 parts metallic aluminum powder; 0.04 parts organic fiber; 1.4 parts functional additives; and 10 parts rare earth core-shell aggregate.

[0052] The main ditch waste undergoes the following screening process: waste with slag and iron adhering to it is picked out; the remaining waste is crushed; the crushed waste is then subjected to magnetic separation to remove iron; and finally, it is placed in a grading screen for further screening. The crushed waste is divided into aggregates with particle sizes of ≤8mm and >5mm, ≤5mm and >3mm, ≤3mm and >1mm, and ≤1mm and >0mm, with a mass ratio of 11:14:12:8. The mass ratio of lithium carbonate to boron carbide in the functional additives is 1:3.

[0053] Preparation process of rare earth core-shell aggregate: S1: Lanthanum phosphate and cerium phosphate were ball-milled and blended with boron oxide. The mass ratio of boron oxide to lanthanum phosphate and cerium phosphate was 4%. The mass ratio of the material, zirconium oxide grinding beads and deionized water in the ball mill was 1:3:1.2. The mixture was ball-milled at 330 r / min until D90 ≤ 3 μm. Then it was vacuum dried at 80℃. After drying, it was pulverized and passed through a 25 μm nylon sieve to obtain the lanthanum phosphate and cerium phosphate mixture. S3: Add 3 wt% PVA to the obtained lanthanum phosphate and cerium phosphate mixture. After mixing evenly, apply a pressure of 150 MPa using a cold isostatic press and hold for 20 min. After pressing, let stand at room temperature for 36 h, and then sinter at a higher temperature. The gradient sintering regime is as follows: First stage: Increase the temperature to 600℃ at a rate of 3℃ / min and hold for 2 hours; Second stage: Increase the temperature to 1700℃ at a rate of 6℃ / min and hold for 7 hours; Third stage: Slowly reduce the furnace temperature to room temperature at a rate of 2℃ / min; S4: The sintered material is crushed into granules with a particle size of 1-3 mm. The granules are immersed in an aluminum sol solution with a mass concentration of 20% for 20 min, and then evenly spread on a sieve and left to stand for 1 h as a bonding layer. The granules are then poured into the mixture (Al2O3 to SiO2 mass ratio of 19:6) and stirred at low speed using a mixer to ensure that each granule is evenly coated. The mixture is then left to stand for 24 h. Finally, the temperature is raised to 1500℃ at a rate of 7℃ / min and held for 5 h to obtain rare earth core-shell aggregate.

[0054] The preparation and performance testing of the test blocks were the same as in Example 1, and the performance is shown in Table 1.

[0055] Example 4 A slag trench spraying material prepared using main ditch waste, comprising the following components and their respective mass percentages: 62 parts main ditch waste; 7 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 5 parts brown fused alumina with a particle size of 45 μm; 10 parts silicon carbide; 2.66 parts calcium aluminate cement; 4 parts alumina micro powder; 2 parts spherical asphalt; 0.9 parts silica micro powder; 0.08 parts metallic aluminum powder; 0.06 parts organic fiber; 1.3 parts functional additives; and 5 parts rare earth core-shell aggregate.

[0056] The main ditch waste undergoes the following screening process: waste with slag and iron adhering to it is picked out; the remaining waste is crushed; the crushed waste is then subjected to magnetic separation to remove iron; and finally, it is placed in a grading screen for further screening. The crushed waste is divided into aggregates with particle sizes less than or equal to 8 mm and greater than 5 mm, less than or equal to 5 mm and greater than 3 mm, less than or equal to 3 mm and greater than 1 mm, and less than or equal to 1 mm and greater than 0 mm, with a mass ratio of 16:17:15:4. The mass ratio of lithium carbonate to boron carbide in the functional additives is 1:3.

[0057] Preparation process of rare earth core-shell aggregate: S1: Lanthanum phosphate and cerium phosphate were ball-milled and blended with boron oxide. The mass ratio of boron oxide to lanthanum phosphate and cerium phosphate was 1 part. The mass ratio of the material, zirconium oxide grinding beads and deionized water in the ball mill was 1:3:1.2. The mixture was ball-milled at 330 r / min until D90≤3μm. Then it was vacuum dried at 80℃. After drying, it was pulverized and passed through a 25μm nylon sieve to obtain the lanthanum phosphate and cerium phosphate mixture. S3: Add 3 wt% PVA to the obtained lanthanum phosphate and cerium phosphate mixture. After mixing evenly, apply a pressure of 150 MPa using a cold isostatic press and hold for 20 min. After pressing, let stand at room temperature for 36 h, and then sinter at a higher temperature. The gradient sintering regime is as follows: First stage: Increase the temperature to 600℃ at a rate of 3℃ / min and hold for 2 hours; Second stage: Increase the temperature to 1700℃ at a rate of 6℃ / min and hold for 7 hours; Third stage: Slowly reduce the furnace temperature to room temperature at a rate of 2℃ / min; S4: The sintered material is crushed into granules with a particle size of 1-3 mm. The granules are immersed in an aluminum sol solution with a mass concentration of 20 parts for 20 min. Then, they are evenly spread on a sieve and left to stand for 1 h as a bonding layer. The granules after standing are poured into the mixture (Al2O3 to SiO2 mass ratio of 19:6) and stirred at low speed using a mixer to ensure that each granule is evenly coated. The mixture is then left to stand for 24 h. Finally, the temperature is raised to 1500℃ at a rate of 7℃ / min and held for 5 h to obtain rare earth core-shell aggregate.

[0058] The preparation and performance testing of the test blocks were the same as in Example 1, and the performance is shown in Table 1.

[0059] Comparative Example 1 A slag trench spraying material prepared using main ditch waste, comprising the following components and their respective mass percentages: 45 parts main ditch waste; 7 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 6 parts brown fused alumina with a particle size of 45 μm; 15 parts silicon carbide; 4 parts calcium aluminate cement; 8 parts alumina micro powder; 2 parts spherical asphalt; 1.5 parts silica micro powder; 0.06 parts metallic aluminum powder; 0.04 parts organic fiber; and 1.4 parts functional additives.

[0060] The main ditch waste underwent the following screening process: waste with slag and iron adhering to it was selected out, the remaining waste was crushed, and the crushed waste was subjected to magnetic separation to remove iron. Then, the waste was placed in a grading screen for further screening, separating it into aggregates with particle sizes of ≤8mm and >5mm, ≤5mm and >3mm, ≤3mm and >1mm, and ≤1mm and >0mm, with a mass ratio of 11:14:12:8. The mass ratio of lithium carbonate to boron carbide in the functional additives was 1:3. The preparation and performance testing of the test blocks were the same as in Example 1, and the performance is shown in Table 1.

[0061] Comparative Example 2 A slag trench spraying material prepared using main trench waste, comprising the following components and their respective mass percentages: 45 parts main trench waste; 7 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 6 parts brown fused alumina with a particle size of 45 μm; 15 parts silicon carbide; 4 parts calcium aluminate cement; 8 parts alumina micro powder; 2 parts spherical asphalt; 1.5 parts silica micro powder; 0.06 parts metallic aluminum powder; 0.04 parts organic fiber; and 10 parts rare earth core-shell aggregate.

[0062] The main ditch waste undergoes the following screening process: waste with slag and iron adhering to it is picked out, the remaining waste is crushed, the crushed waste is subjected to magnetic separation to remove iron, and then the waste is placed in a grading screen for screening. The crushed waste is divided into aggregates with a particle size of less than or equal to 8 mm and greater than 5 mm, less than or equal to 5 mm and greater than 3 mm, less than or equal to 3 mm and greater than 1 mm, and less than or equal to 1 mm and greater than 0 mm. The mass ratio of the aggregates is 11:14:12:8.

[0063] Preparation process of rare earth core-shell aggregate: S1: Lanthanum phosphate and cerium phosphate were ball-milled and blended with boron oxide. The mass ratio of boron oxide to lanthanum phosphate and cerium phosphate was 4%. The mass ratio of the material, zirconium oxide grinding beads and deionized water in the ball mill was 1:3:1.2. The mixture was ball-milled at 330 r / min until D90 ≤ 3 μm. Then it was vacuum dried at 80℃. After drying, it was pulverized and passed through a 25 μm nylon sieve to obtain the lanthanum phosphate and cerium phosphate mixture. S3: Add 3 wt% PVA to the obtained lanthanum phosphate and cerium phosphate mixture. After mixing evenly, apply a pressure of 150 MPa using a cold isostatic press and hold for 20 min. After pressing, let stand at room temperature for 36 h, and then sinter at a higher temperature. The gradient sintering regime is as follows: First stage: Increase the temperature to 600℃ at a rate of 3℃ / min and hold for 2 hours; Second stage: Increase the temperature to 1700℃ at a rate of 6℃ / min and hold for 7 hours; Third stage: Slowly reduce the furnace temperature to room temperature at a rate of 2℃ / min; S4: The sintered material is crushed into granules with a particle size of 1-3 mm. The granules are immersed in an aluminum sol solution with a mass concentration of 20% for 20 min, and then evenly spread on a sieve and left to stand for 1 h as a bonding layer. The granules are then poured into the mixture (Al2O3 to SiO2 mass ratio of 19:6) and stirred at low speed using a mixer to ensure that each granule is evenly coated. The mixture is then left to stand for 24 h. Finally, the temperature is raised to 1500℃ at a rate of 7℃ / min and held for 5 h to obtain rare earth core-shell aggregate.

[0064] The preparation and performance testing of the test blocks were the same as in Example 1, and the performance is shown in Table 1.

[0065] Comparative Example 3 A slag trench spraying material prepared using main ditch waste, comprising the following components and their respective mass percentages: 45 parts main ditch waste; 7 parts brown fused alumina with a particle size less than or equal to 15 mm and greater than 8 mm; 6 parts brown fused alumina with a particle size of 45 μm; 15 parts silicon carbide; 4 parts calcium aluminate cement; 8 parts alumina micro powder; 2 parts spherical asphalt; 1.5 parts silica micro powder; 0.06 parts metallic aluminum powder; and 0.04 parts organic fiber.

[0066] The main ditch waste underwent the following screening process: waste with slag and iron adhering to it was picked out, the remaining waste was crushed, and the crushed waste was subjected to magnetic separation to remove iron. Then, the waste was placed in a grading screen for further screening, separating it into aggregates with particle sizes of ≤8mm and >5mm, ≤5mm and >3mm, ≤3mm and >1mm, and ≤1mm and >0mm, with a mass ratio of 11:14:12:8. The preparation and performance testing of the test blocks were the same as in Example 1, and the performance is shown in Table 1.

[0067] Comparative Example 4 The difference from Example 1 is that lanthanum oxide and boron oxide are ball-milled and blended in the preparation process of rare earth core-shell aggregate, while the other process steps are the same as in Example 1.

[0068] Comparative Example 5 The difference from Example 1 is that lanthanum cerium phosphate powder is directly pressurized and molded in the preparation process of rare earth core-shell aggregate, while the other process steps are the same as in Example 1.

[0069] The bulk density of the sprayed material was determined using the method in GB / T 2997-2015; the thermal conductivity of the sprayed material was determined using the method in GB / T 5990-2021; the room temperature compressive strength of the sprayed material was determined using the method in GB / T 5072-2023; the room temperature flexural strength of the sprayed material was determined using the method in GB / T 3001-2017; the permanent linear shrinkage rate of the sprayed material was determined using the method in GB / T 5988-2022; and the resistance to slag and iron erosion was determined using the method in GB / T 8931-2007 (static crucible method).

[0070] Table 1: Performance Data Sheet

[0071] The data above shows that the addition of rare earth core-shell aggregate and functional additives can help improve the mechanical strength, density and erosion rate of the material after sintering. Because rare earth phosphate has low thermal conductivity, the thermal insulation performance of the material is greatly enhanced after the addition of rare earth core-shell aggregate, while the linear change rate decreases by about half, ensuring the bonding between the sprayed material and the original groove material.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 slag trench spraying material prepared using waste from the main trench, characterized in that: The total quantity is 100 servings, comprising the following components by weight: Main ditch waste 45-62 parts, brown corundum 12-20 parts, silicon carbide 10-15 parts, calcium aluminate cement 2-4 parts, alumina powder 4-8 parts, spherical asphalt 2-5 parts, silica powder 0.9-1.5 parts, metallic aluminum powder 0.02-0.08 parts, organic fiber 0.04-0.08 parts, functional additives 1.3-1.7 parts, rare earth core-shell aggregate 5-10 parts.

2. The slag trench spraying material prepared from main trench waste according to claim 1, characterized in that: The main ditch waste undergoes the following screening process: waste with slag and iron adhering to it is picked out, the remaining waste is crushed, the crushed waste is subjected to magnetic separation to remove iron, and then the waste is placed in a grading screen for screening. The crushed waste is divided into aggregates with particle sizes less than or equal to 8 mm and greater than 5 mm, less than or equal to 5 mm and greater than 3 mm, less than or equal to 3 mm and greater than 1 mm, and less than or equal to 1 mm and greater than 0 mm. The weight parts added are 11-16 parts, 14-17 parts, 12-15 parts, and 8-14 parts, respectively.

3. The slag trench spraying material prepared from main trench waste according to claim 1, characterized in that: The method for preparing rare earth core-shell aggregate includes the following steps: S1: Lanthanum phosphate and boron oxide were ball-milled and blended until D90≤3μm, then vacuum dried, and then pulverized and sieved to obtain a mixture of lanthanum phosphate and cerium oxide. S2: Add polyvinyl alcohol to the obtained lanthanum phosphate and cerium phosphate mixture, mix thoroughly, and then cold isostatically press under a pressure of 100-150 MPa for 20-40 min. After pressing, let stand at room temperature for 24-36 h, and then perform temperature-raising sintering. The gradient sintering process is as follows: First stage: Heat to 600℃ at a heating rate of 2-3℃ / min, and hold for 1-2 hours; Second stage: Heat to 1650-1700℃ at a heating rate of 4-6℃ / min, hold for 7-10h, and then sinter and densify under normal pressure. The third stage: cooling down to room temperature at a rate of 2℃ / min; S3: The sintered material is crushed into granules with a particle size of 1-3mm. The granules are immersed in an aluminum sol solution and then left to stand for 1-5 hours. The granules are then poured into a mixed powder of Al2O3 and SiO2, stirred, and left to stand for 20-24 hours. Finally, the temperature is raised to 1450-1500℃ at a heating rate of 4-7℃ / min and held for 5-7 hours to form a dense mullite shell on the surface of the granules, thus obtaining rare earth core-shell aggregate.

4. The slag trench spraying material prepared from main trench waste according to claim 3, characterized in that: In step S1, the mass ratio of boron oxide to lanthanum phosphate is 1%-4%.

5. The slag trench spraying material prepared from main trench waste according to claim 3, characterized in that: In step S3, the mass ratio of Al2O3 to SiO2 in the mixed powder is (17-19):(6-8).

6. The slag trench spraying material prepared from main trench waste according to claim 1, characterized in that: The brown fused alumina contains ≥90wt% alumina; wherein, the weight percentage of brown fused alumina with a particle size of ≤15mm and >8mm is 7-12 parts, and the weight percentage of brown fused alumina with a particle size of 45μm is 5-8 parts.

7. The slag trench spraying material prepared from main trench waste according to claim 1, characterized in that: The calcium aluminate cement has an Al2O3 content of ≥70wt% and a particle size of <45μm. The alumina micro powder contains ≥98wt% α-Al2O3 and has a particle size ≤6.5μm.

8. The slag trench spraying material prepared from main trench waste according to claim 1, characterized in that: The silicon micropowder contains ≥94 wt% SiO2 and has a particle size ≤0.5 μm. The aluminum powder contains ≥99 wt% aluminum and has a particle size ≤0.5 μm. The organic fiber is a polypropylene fiber with a length of 3-5 mm and a diameter of 40 μm.

9. The slag trench spraying material prepared from main trench waste according to claim 1, characterized in that: The functional additives include lithium carbonate and boron carbide in a mass ratio of 1:(1-3), and the particle size of the functional additives is ≤0.074mm.

10. The construction method of the slag trench spraying material prepared from the main trench waste as described in any one of claims 1-9, characterized in that: The process includes the following steps: mixing the main ditch waste, brown corundum, silicon carbide, calcium aluminate cement, alumina powder, spherical asphalt, silica powder, metallic aluminum powder, organic fiber, functional additives, and rare earth core-shell aggregate evenly to obtain powder, then adding water accounting for 4% to 8% of the total mass of the powder, mixing and stirring to form a slurry, and then pumping the slurry through a conveying pipeline to the nozzle of the spraying machine, and then using high-pressure air to spray the mixed slurry onto the damaged surface of the slag ditch that needs to be repaired through the nozzle.

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