Composite drain brick using silica system as non-working area raw material and preparation method thereof

Abstract

The present invention relates to the technical field of refractory material preparation, and in particular to a composite drain brick using a silica system as raw material for a non-working area and a preparation method thereof. The composite drain brick includes a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area. The working area includes the following raw materials in parts by weight: 70-80 parts of high-alumina bauxite aggregate, 10-25 parts of white corundum powder, 3-6 parts of graphite and carbon black, 3-5 parts of silicon carbide, 1-2 parts of metallic silicon powder, and 3-5 parts of phenolic resin; the non-working area includes the following raw materials in parts by weight: 20-30 parts of high-alumina bauxite aggregate, 50-60 parts of silica aggregate, 10-20 parts of silica fine powder, 2-6 parts of graphite and carbon black, and 3-5 parts of phenolic resin. The present invention provides a non-working area outside the working area of ​​the composite drain brick. The raw material of the non-working area is based on a silica system. The unique crystal phase transition, volume expansion and low thermal conductivity of silica are utilized to buffer the working area of ​​the drain brick, thereby achieving the purpose of preventing crack expansion and improving the service life of the drain brick.

Description

Technical Field

[0001] The invention relates to the technical field of refractory material preparation, in particular to a composite drain brick using a silica system as a non-working zone raw material and a preparation method thereof. Background Art

[0002] With the development of large-scale ladles and off-furnace refining technology, my country has made great progress in the research and production of sliding nozzles to meet the needs of smelting processes. As an important container for molten steel, the ladle plays a key role in connecting the converter and continuous casting. The sliding nozzle is a functional refractory material installed at the bottom of the ladle for opening and closing the steel flow and controlling the flow rate. It consists of an upper nozzle, an upper slide, a lower slide, and a lower nozzle. Its task is to safely and normally cast the molten steel from the converter into the tundish of the continuous casting. If steel leaks from this part, it will affect the quality of the molten steel at the least, and may cause the casting machine to stop pouring or even cause personal injury accidents at the worst, affecting both production and threatening personnel safety.

[0003] Thermomechanical corrosion and thermochemical erosion are the two main mechanisms of sliding nozzle damage. Among them, thermomechanical corrosion is caused by the thermal shock effect on the slide body caused by the huge temperature difference between the sliding nozzle and the high-temperature molten steel during the casting process. The thermal shock resistance of the slide can be improved by introducing other substances into the matrix to reduce the elastic modulus of the refractory material, or increase the thermal stress fracture coefficient and crack stress resistance coefficient; thermochemical erosion is caused by the slide contacting high-temperature molten steel and slag during use, resulting in a series of chemical reactions. Generally, there are chemical erosions of Ca-treated steel, high-Mn steel, slag, and chemical changes of substances contained in the refractory material itself.

[0004] Thermomechanical corrosion theory mainly includes thermal shock fracture theory and thermal shock damage theory. The first one focuses on the problem of crack formation, and the second one focuses on the problem of crack propagation.

[0005] The initial thermal stress fracture coefficient R can be obtained using Kingery's thermoelastic theory.

[0006] R=S(1-μ) / Ea

[0007] Once a crack is generated and continues to expand, according to Hasslman fracture mechanics theory, the resistance coefficient of this crack stress is RSt:

[0008] RSt=[y(1-μ) / Eoa2]1 / 2

[0009] Where S-tensile strength MPa, E-elastic modulus MPa, μ-Poisson's ratio, Eo-elastic modulus without crack MPa, a-thermal expansion coefficient, R-fracture energy N·m -2 .

[0010] It can be seen from the above two formulas that the thermal expansion coefficient and elastic modulus of the material are inversely related to the thermal stress fracture coefficient R and the crack stress resistance coefficient RSt. By reducing the thermal expansion coefficient and elastic modulus of the material, the material can obtain better thermal shock stability because crack generation and expansion become difficult.

[0011] During use, the nozzle experiences compressive stress near the inner hole and tensile stress near the outer surface. Fracture is most likely to occur within two minutes after the start of molten steel pouring. Over time, the outer surface temperature gradually rises, the temperature gradient decreases, and the stress decreases. Refractory materials are multiphase loose bodies with a large number of pores and grain boundaries, making crack sources very likely to form. These pores and grain boundaries can also absorb energy, releasing the energy required for crack propagation. Therefore, for nozzles, crack propagation is the limiting factor in material failure.

[0012] Chinese patent 201710237020.4 discloses a magnesium spinel brick with excellent anti-stripping performance and its preparation method, which uses carbon black to modify the surface of the aggregate and introduces spinel to combine with magnesia. The thermal expansion coefficient of the magnesium spinel brick is significantly reduced without affecting the slag resistance, which can significantly improve the anti-stripping performance of the product; however, the invention uses magnesia as the main raw material, which is easily hydrated in a humid environment, and the main raw material of magnesia is MgO, which has a large thermal expansion coefficient, and the obtained product is prone to cracking. The steel shell added to the water outlet currently used in production can effectively prevent the expansion of cracks, but after repeated use, the surface temperature of the steel shell increases, the steel shell deforms, and the binding force of the steel shell on the water outlet is weakened. In severe cases, the steel shell may fall off, causing a production accident. Therefore, a new means is needed to effectively prevent the expansion of cracks and ensure production safety. Summary of the Invention

[0013] In order to solve the above problems, the present invention provides a composite drain brick with a silica system as the raw material for the non-working area and a preparation method thereof. By introducing silica raw material into the non-working surface of the composite drain, the unique crystal phase transformation, volume expansion and low thermal conductivity of silica are utilized to achieve the purpose of preventing crack propagation.

[0014] In order to achieve the above object, the present invention adopts the following technical solutions:

[0015] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area,

[0016] The working area includes the following raw materials in parts by weight: 70-80 parts of high-alumina bauxite aggregate, 10-25 parts of white corundum powder, 3-6 parts of graphite and carbon black, 3-5 parts of silicon carbide, 1-2 parts of metallic silicon powder, and 3-5 parts of phenolic resin;

[0017] The non-working area comprises the following raw materials in parts by weight: 20-30 parts of high-alumina bauxite aggregate, 50-60 parts of silica aggregate, 10-20 parts of silica fine powder, 2-6 parts of graphite and carbon black, and 3-5 parts of phenolic resin.

[0018] In some preferred embodiments, the working area includes the following raw materials in parts by weight: 70-75 parts of high-alumina bauxite aggregate, 16-22 parts of white corundum powder, 4-6 parts of graphite and carbon black, 3-4 parts of silicon carbide, 1-2 parts of metallic silicon powder, and 3-5 parts of phenolic resin;

[0019] The non-working area comprises the following raw materials in parts by weight: 20-25 parts of high-alumina bauxite aggregate, 50-55 parts of silica aggregate, 15-20 parts of silica fine powder, 4-5 parts of graphite and carbon black, and 3-5 parts of phenolic resin.

[0020] In some embodiments, the purity of high-alumina bauxite aggregate in the raw materials of the working zone is ≥85%, and the aggregate is composed of 0mm-1mm particles and 1mm-3mm particles in a mass ratio of 1:(1-1.5); the purity of high-alumina bauxite aggregate in the raw materials of the non-working zone is ≥80%, and the particle size is 1mm-3mm.

[0021] In some embodiments, the raw materials in the non-working area have a purity of silica aggregate ≥ 95%, and are composed of 0mm-1mm particles and 1mm-3mm particles in a mass ratio of 1:(1.2-1.6).

[0022] In some embodiments, in the raw materials of the non-working zone, the ratio of the mass of silica aggregate to the mass of silica fine powder to the mass of high-alumina bauxite is (2-3):1.

[0023] In some embodiments, the particle size of the white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica powder is ≤0.088 mm.

[0024] In some embodiments, the total mass ratio of the raw materials in the working area to the raw materials in the non-working area is (50-55): (45-50).

[0025] In some embodiments, the non-working area is surrounded by the working area and the steel shell; the thermal expansion rate of the non-working area is greater than the thermal expansion rate of the working area.

[0026] Specifically, the distance from the bottom of the non-working area to the bottom of the composite drain brick is 40mm-60mm; the distance from the top of the non-working area to the opening of the composite drain brick is 10mm-15mm; the thickness of the working area is 15mm-20mm;

[0027] In some preferred embodiments, the ratio of the thermal expansion rate of the non-working area to the thermal expansion rate of the working area is (3-6): 1. In some more preferred embodiments, the ratio of the thermal expansion rate of the non-working area to the thermal expansion rate of the working area is (3-5): 1.

[0028] Specifically, in the composite drain brick of the present application, the thermal expansion rate of the non-working area at 1200° C. is 0.6%-0.9%, and the thermal expansion rate of the working area at 1200° C. is 0.1%-0.3%.

[0029] The present invention also provides a method for preparing the composite drain brick, comprising the following steps:

[0030] (1) Mixing: Weigh the raw material components of the working area and non-working area according to the ratio, put them into the mixer and mix them evenly;

[0031] (2) Material trapping: Tie the bag mouth of the evenly mixed mud material to trap the material;

[0032] (3) Molding: pour the trapped working and non-working materials into the working and non-working cavities of the mold respectively, pressurize and shape them to obtain semi-finished bricks;

[0033] (4) Drying and shelling: The semi-finished bricks are dried, shelled, and dried again to obtain composite drain bricks.

[0034] In some embodiments, in step (1), the total mixing time of the raw material components in the working area and the non-working area is 36 minutes to 50 minutes respectively; in step (2), the material confinement time is 24 hours to 48 hours respectively; in step (3), a 630-ton screw press is used for molding; in step (4), a 180°C to 200°C drying kiln is used for drying.

[0035] In some embodiments, in step (3), the trapped working fabric is poured into the working chamber twice, before and after the non-working fabric; and the press molding is performed by lightly hitting 2-3 times and then hitting 6-8 times to obtain a semi-finished brick.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The composite drain brick provided by the present invention is provided with a non-working area outside the working area. The raw material of the non-working area is based on the silica system. The unique crystal phase transformation, volume expansion and low thermal conductivity of silica are utilized to buffer the working area of ​​the drain brick. On the one hand, the temperature of the steel shell is reduced, the deformation of the steel shell is weakened, and the restraint force of the steel shell on the drain brick is prevented from weakening after repeated use, thereby achieving the purpose of preventing cracks from expanding. On the other hand, the volume expansion characteristic of the silica raw material is utilized to act on the injection hole to prevent the cracks from expanding on the contact surface of the working area. Moreover, after the non-working area expands, it directly acts on the steel shell to squeeze the steel shell. At the same time, the steel shell gives a reaction force to the non-working area, which can also restrain the drain brick and prevent its cracks from expanding.

[0038] (2) The present invention further controls the raw material ratio of the non-working area of ​​the composite drain brick, further limits the raw material content of the non-working area and the working area, and further limits the relative position of the non-working area and the working area, thereby controlling the difference in expansion coefficient between the non-working area and the working area within an optimal range. This allows the prepared composite drain brick to have uniform stress dispersion during actual use, thereby achieving the best crack resistance. The composite drain brick prepared by the present invention has an actual average service life increased by 1-3 times compared to existing drain bricks, which should have a good effect and greatly reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 The figure is a structural schematic diagram of the composite drain brick of the present invention.

[0041] Among them: 1-working area, 2-non-working area. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions of the present invention in conjunction with specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0043] Example 1

[0044] A composite drain brick, such as Figure 1 As shown, it includes a working area and a non-working area, and the non-working area is arranged on the periphery of the working area and is surrounded by the working area and the steel shell;

[0045] The working area includes the following raw materials by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 30 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 21 parts of white corundum powder, 2 parts of graphite, 2 parts of carbon black, 3 parts of silicon carbide, 2 parts of metallic silicon powder, and 3 parts of phenolic resin;

[0046] The non-working area includes the following raw materials in parts by weight: 20 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 22 parts of 1mm-3mm silica aggregate, 33 parts of 0mm-1mm silica aggregate, 20 parts of silica fine powder, 2 parts of graphite, 3 parts of carbon black, and 3 parts of phenolic resin.

[0047] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder is ≤0.088mm. The total mass ratio of raw materials in the working area to that in the non-working area is 55:45.

[0048] The preparation method of the composite drain brick comprises the following steps:

[0049] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0050] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to allow the binder to fully cover the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0051] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0052] (3) Molding: Add the materials together into the mold, 40 mm from the bottom, to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it again 6 times to take out the bricks to obtain semi-finished bricks;

[0053] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0054] Example 2

[0055] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area and is surrounded by the working area and a steel shell;

[0056] The working area includes the following raw materials by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 33 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 16 parts of white corundum powder, 3 parts of graphite, 2 parts of carbon black, 4 parts of silicon carbide, 2 parts of metallic silicon powder, and 4 parts of phenolic resin;

[0057] The non-working area includes the following raw materials in parts by weight: 24 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 25 parts of 1mm-3mm silica aggregate, 30 parts of 0mm-1mm silica aggregate, 15 parts of silica fine powder, 3 parts of graphite, 3 parts of carbon black, and 4 parts of phenolic resin.

[0058] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder is ≤0.088mm. The total mass ratio of raw materials in the working area to non-working area is 52:48.

[0059] The preparation method of the composite drain brick comprises the following steps:

[0060] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 4 minutes, then add the phenolic resin binder and mix for 4 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 35 minutes;

[0061] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 4 minutes, then add the phenolic resin binder and mix for 4 minutes to allow the binder to fully cover the aggregate particles, finally add the premixed powder and continue mixing for 35 minutes;

[0062] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0063] (3) Molding: Add the materials into the mold to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it again 7 times to take out the bricks to obtain semi-finished bricks;

[0064] (4) Drying and shelling: The semi-finished bricks are dried in a 190°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0065] Example 3

[0066] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area and is surrounded by the working area and a steel shell;

[0067] The working area includes the following raw materials by weight: 43 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 35 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 12 parts of white corundum powder, 2 parts of graphite, 3 parts of carbon black, 4 parts of silicon carbide, 1 part of metallic silicon powder, and 5 parts of phenolic resin;

[0068] The non-working area includes the following raw materials in parts by weight: 28 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 23 parts of 1mm-3mm silica aggregate, 35 parts of 0mm-1mm silica aggregate, 10 parts of silica fine powder, 2 parts of graphite, 2 parts of carbon black, and 4 parts of phenolic resin.

[0069] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder shall be ≤0.088mm. The total mass ratio of raw materials in the working area and non-working area shall be 50:50.

[0070] The preparation method of the composite drain brick comprises the following steps:

[0071] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 5 minutes, then add the phenolic resin binder and mix for 5 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 40 minutes;

[0072] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 5 minutes, then add the phenolic resin binder and mix for 5 minutes to allow the binder to fully cover the aggregate particles, finally add the premixed powder and continue mixing for 40 minutes;

[0073] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 48 hours;

[0074] (3) Molding: Add the materials into the mold to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it 8 times to remove the bricks to obtain semi-finished bricks;

[0075] (4) Drying and shelling: The semi-finished bricks are dried in a 200°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0076] Example 4

[0077] The difference between this embodiment and embodiment 1 is that the proportion of raw materials in the working area and the non-working area is different, as follows:

[0078] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area and is surrounded by the working area and a steel shell;

[0079] The working area includes the following raw materials by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 30 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 21 parts of white corundum powder, 2 parts of graphite, 2 parts of carbon black, 3 parts of silicon carbide, 2 parts of metallic silicon powder, and 3 parts of phenolic resin;

[0080] The non-working area includes the following raw materials in parts by weight: 20 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 22 parts of 1mm-3mm silica aggregate, 33 parts of 0mm-1mm silica aggregate, 20 parts of silica fine powder, 2 parts of graphite, 3 parts of carbon black, and 3 parts of phenolic resin.

[0081] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder is ≤0.088mm. The total mass ratio of raw materials in the working area to that in the non-working area is 65:35.

[0082] The preparation method of the composite drain brick comprises the following steps:

[0083] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0084] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to allow the binder to fully cover the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0085] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0086] (3) Molding: Add the materials into the mold to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it again 6 times to take out the bricks to obtain semi-finished bricks;

[0087] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0088] Example 5

[0089] The difference between this embodiment and embodiment 1 is that the proportion of raw materials in the working area and the non-working area is different, as follows:

[0090] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area and is surrounded by the working area and a steel shell;

[0091] The working area includes the following raw materials by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 30 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 21 parts of white corundum powder, 2 parts of graphite, 2 parts of carbon black, 3 parts of silicon carbide, 2 parts of metallic silicon powder, and 3 parts of phenolic resin;

[0092] The non-working area includes the following raw materials in parts by weight: 20 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 22 parts of 1mm-3mm silica aggregate, 33 parts of 0mm-1mm silica aggregate, 20 parts of silica fine powder, 2 parts of graphite, 3 parts of carbon black, and 3 parts of phenolic resin.

[0093] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder is ≤0.088mm. The total mass ratio of raw materials in the working area to that in the non-working area is 35:65.

[0094] The preparation method of the composite drain brick comprises the following steps:

[0095] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0096] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to allow the binder to fully cover the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0097] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0098] (3) Molding: Add the materials into the mold to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it again 6 times to take out the bricks to obtain semi-finished bricks;

[0099] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0100] Comparative Example 1

[0101] The difference between this comparative example and Example 1 is that it does not contain non-working fabrics, specifically as follows:

[0102] A drain brick comprises the following raw materials in parts by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 30 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 21 parts of white corundum powder, 2 parts of graphite, 2 parts of carbon black, 3 parts of silicon carbide, 2 parts of metallic silicon powder, and 3 parts of phenolic resin.

[0103] Among them, the particle size of white corundum powder, graphite, carbon black, silicon carbide and metallic silicon powder is ≤0.088mm.

[0104] The preparation method of the above-mentioned drain brick comprises the following steps:

[0105] (1) Mixing: Weigh the raw materials according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0106] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0107] (3) Molding: Pour the trapped raw materials into the mold, tamp them with a steel chisel, and then use a 630-ton screw press to hit them lightly twice to fully exhaust the air, and then hit them again 6 times to produce bricks to obtain semi-finished bricks;

[0108] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain drain bricks.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 1 is that it does not contain working fabrics, specifically as follows:

[0111] A drain brick comprises the following raw materials in parts by weight: 20 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 22 parts of 1mm-3mm silica aggregate, 33 parts of 0mm-1mm silica aggregate, 20 parts of silica fine powder, 2 parts of graphite, 3 parts of carbon black, and 3 parts of phenolic resin.

[0112] Among them, the particle size of graphite, carbon black and silica fine powder is ≤0.088mm.

[0113] The preparation method of the above-mentioned drain brick comprises the following steps:

[0114] (1) Mixing: Weigh the raw materials according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0115] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0116] (3) Molding: Pour the trapped raw materials into the mold, tamp them with a steel chisel, and then use a 630-ton screw press to hit them lightly twice to fully exhaust the air, and then hit them again 6 times to produce bricks to obtain semi-finished bricks;

[0117] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain drain bricks.

[0118] Comparative Example 3

[0119] The difference between this comparative example and Example 1 is that the contents of silica and silica fine powder in the non-working fabric are different, as follows:

[0120] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area and is surrounded by the working area and a steel shell;

[0121] The working area includes the following raw materials by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 30 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 21 parts of white corundum powder, 2 parts of graphite, 2 parts of carbon black, 3 parts of silicon carbide, 2 parts of metallic silicon powder, and 3 parts of phenolic resin;

[0122] The non-working area includes the following raw materials in parts by weight: 35 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 15 parts of 1mm-3mm silica aggregate, 25 parts of 0mm-1mm silica aggregate, 20 parts of silica fine powder, 2 parts of graphite, 3 parts of carbon black, and 3 parts of phenolic resin.

[0123] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder is ≤0.088mm. The total mass ratio of raw materials in the working area to that in the non-working area is 55:45.

[0124] The preparation method of the composite drain brick comprises the following steps:

[0125] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0126] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to allow the binder to fully cover the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0127] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0128] (3) Molding: Add the materials into the mold to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it again 6 times to take out the bricks to obtain semi-finished bricks;

[0129] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0130] Comparative Example 4

[0131] The difference between this comparative example and Example 1 is that the contents of silica and silica fine powder in the non-working fabric are different, as follows:

[0132] A composite drain brick comprises a working area and a non-working area, wherein the non-working area is arranged on the periphery of the working area and is surrounded by the working area and a steel shell;

[0133] The working area includes the following raw materials by weight: 40 parts of 1mm-3mm A85 high-alumina bauxite aggregate, 30 parts of 0mm-1mm A85 high-alumina bauxite aggregate, 21 parts of white corundum powder, 2 parts of graphite, 2 parts of carbon black, 3 parts of silicon carbide, 2 parts of metallic silicon powder, and 3 parts of phenolic resin;

[0134] The non-working area includes the following raw materials in parts by weight: 15 parts of 1mm-3mm A80 high-alumina bauxite aggregate, 25 parts of 1mm-3mm silica aggregate, 35 parts of 0mm-1mm silica aggregate, 20 parts of silica fine powder, 2 parts of graphite, 3 parts of carbon black, and 3 parts of phenolic resin.

[0135] The particle size of white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder, and silica fine powder is ≤0.088mm. The total mass ratio of raw materials in the working area to that in the non-working area is 55:45.

[0136] The preparation method of the composite drain brick comprises the following steps:

[0137] (1) Mixing: Weigh the raw materials in the working area according to the proportion, add the fine powder with a particle size of ≤0.088 mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size of >0.088 mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to ensure that the binder fully covers the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0138] Weigh the components of the non-working area raw materials according to the ratio, add the fine powder with a particle size of ≤0.088mm into the mixer and mix thoroughly to obtain a premixed powder for use, then add all the aggregates with a particle size greater than 0.088mm into the planetary wheel mill and mix for 3 minutes, then add the phenolic resin binder and mix for 3 minutes to allow the binder to fully cover the aggregate particles, and finally add the premixed powder and continue mixing for 30 minutes;

[0139] (2) Material trapping: Tie the mixed mud into bags and trap the mud for 36 hours;

[0140] (3) Molding: Add the materials into the mold to form a working cavity and a non-working cavity; weigh 60% of the trapped working material and pour it into the working cavity in the feeding bucket, then pour the trapped non-working material into the non-working cavity between the feeding bucket and the mold, and pour the remaining 40% of the working material into the working cavity. Slowly withdraw the feeding bucket so that the working material is flat on the top, and then tamp it with a steel chisel; finally, use a 630-ton screw press to lightly hit it twice to fully exhaust the air, and then hit it again 6 times to take out the bricks to obtain semi-finished bricks;

[0141] (4) Drying and shelling: The semi-finished bricks are dried in a 180°C drying kiln, shelled, and dried again to obtain composite drain bricks.

[0142] The performance tests were conducted on the drain bricks prepared in Examples 1-5 and Comparative Examples 1-4. The test results are shown in Table 1:

[0143] Table 1

[0144]

[0145] Examples 1-5 are composite drain bricks prepared according to the present invention. After testing, the thermal expansion rates of the non-working area at 1200°C for 1h, 1.5h, and 2h are 0.67%-0.80%, 0.69%-0.86%, and 0.71%-0.85%, respectively; the thermal expansion rates of the working area at 1200°C for 1h, 1.5h, and 2h are 0.12%-0.22%, 0.15%-0.25%, and 0.14%-0.24%, respectively. The service life of the prepared composite drain bricks is 2-4 times.

[0146] Comparing Example 1 and Example 4-5, the proportion of raw materials in the non-working area in Example 4 is 35%, and the content of fabric in the non-working area of ​​the drain brick is relatively low, which makes the non-working area of ​​the composite drain brick thinner, resulting in a lower overall expansion rate, a smaller reaction force on the steel shell, insufficient binding force of the steel shell, and cracks in the non-working surface area; the proportion of raw materials in the non-working area in Example 5 is 65%, and the content of fabric in the non-working area in the drain brick is relatively high, which makes the working area of ​​the composite drain brick thinner, resulting in insufficient strength of the working fabric, making it difficult to withstand the expansion force of the non-working fabric, and easily causing cracks at the casting hole, causing erosion pits.

[0147] Comparing Example 1 and Comparative Examples 1-2, both Comparative Examples 1 and 2 have a single structural layer and do not have a non-working area, so the non-working area cannot be used for buffering. Comparative Example 1 is entirely working fabric, which has high strength and is very prone to cracks during use. Moreover, the steel shell is affected by high temperature during use, and its strength decreases, making it unable to effectively restrain the bricks and prevent cracks from expanding. Comparative Example 2 directly uses fabric containing silica as the working fabric, which has extremely poor corrosion resistance and cannot be used normally.

[0148] Comparing Example 1 and Comparative Examples 3-4, the silica content in the non-working area of ​​Comparative Example 3 is relatively low, resulting in a relatively low thermal expansion coefficient of the non-working area. The difference in thermal expansion performance between the non-working area and the working area is small, and the difference in expansion coefficients between the two cannot be effectively utilized to prevent the expansion of microcracks; the silica content in the non-working area of ​​Comparative Example 4 is relatively high, resulting in the thermal expansion coefficient of the non-working area being much greater than the thermal expansion coefficient of the working area, making the working area unable to withstand the extrusion of the non-working area, causing cracks to form at the casting hole and reducing the service life.

[0149] The drain bricks prepared by the present invention have been successfully used. According to calculations, compared with the original drain bricks, the formula cost is reduced by 800-1200 yuan per ton, and the service life is increased by 1-3 times compared with the original formula. While the product stability is improved, the cost is greatly saved and the application effect is good.

[0150] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A composite drain brick, characterized in that: It includes a working area and a non-working area, wherein the non-working area is arranged outside the working area, The working area includes the following raw materials in parts by weight: 70-80 parts of high-alumina bauxite aggregate, 10-25 parts of white corundum powder, 3-6 parts of graphite and carbon black, 3-5 parts of silicon carbide, 1-2 parts of metallic silicon powder, and 3-5 parts of phenolic resin; The non-working area comprises the following raw materials in parts by weight: 20-30 parts of high-alumina bauxite aggregate, 50-60 parts of silica aggregate, 10-20 parts of silica fine powder, 2-6 parts of graphite and carbon black, and 3-5 parts of phenolic resin; The total mass ratio of the raw materials in the working area to those in the non-working area is (50-55): (45-50).

2. The composite drain brick according to claim 1, characterized in that: The working area includes the following raw materials in parts by weight: 70-75 parts of high-alumina bauxite aggregate, 16-22 parts of white corundum powder, 4-6 parts of graphite and carbon black, 3-4 parts of silicon carbide, 1-2 parts of metallic silicon powder, and 3-5 parts of phenolic resin; The non-working area comprises the following raw materials in parts by weight: 20-25 parts of high-alumina bauxite aggregate, 50-55 parts of silica aggregate, 15-20 parts of silica fine powder, 4-5 parts of graphite and carbon black, and 3-5 parts of phenolic resin.

3. The composite drain brick according to claim 1, characterized in that: Among the raw materials in the working area, the purity of high-alumina bauxite aggregate is ≥85%, and it is composed of 0mm-1mm particles and 1mm-3mm particles in a mass ratio of 1:(1-1.5); among the raw materials in the non-working area, the purity of high-alumina bauxite aggregate is ≥80%, and the particle size is 1mm-3mm.

4. The composite drain brick according to claim 1, characterized in that: Among the raw materials in the non-working area, the purity of the silica aggregate is ≥95%, and it is composed of 0mm-1mm particles and 1mm-3mm particles in a mass ratio of 1:(1.2-1.6).

5. The composite drain brick according to claim 1, characterized in that: The particle size of the white corundum powder, graphite and carbon black, silicon carbide, metallic silicon powder and silica powder is ≤0.088 mm.

6. The composite drain brick according to claim 1, characterized in that: The non-working area is surrounded by the working area and the steel shell; and the thermal expansion rate of the non-working area is greater than the thermal expansion rate of the working area.

7. The composite drain brick according to claim 6, characterized in that: The ratio of the thermal expansion coefficient of the non-working area to the thermal expansion coefficient of the working area is (3-6):

1.

8. A method for preparing the composite drain brick according to any one of claims 1 to 7, characterized in that: The steps include: (1) Mixing: Weigh the raw material components of the working area and non-working area according to the ratio, put them into the mixer and mix them evenly; (2) Material trapping: Tie the bag mouth of the evenly mixed mud material to trap the material; (3) Molding: Pour the trapped working and non-working materials into the working and non-working cavities of the mold respectively, pressurize and shape them to obtain semi-finished bricks; (4) Drying and shelling: The semi-finished bricks are dried, shelled, and dried again to obtain composite drain bricks.

9. The method for preparing a composite drain brick according to claim 8, characterized in that: In step (1), the total mixing time of the raw material components in the working area and the non-working area is 36 minutes to 50 minutes respectively; in step (2), the material confinement time is 24 hours to 48 hours respectively; in step (3), a 630-ton screw press is used for forming; in step (4), a 180°C to 200°C drying kiln is used for drying.

10. The method for preparing a composite drain brick according to claim 8, characterized in that: In step (3), the trapped working surface material is poured into the working cavity twice before and after the non-working surface material; the pressure molding is performed by lightly hitting 2-3 times and then hitting 6-8 times to obtain a semi-finished brick.

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