Green energy-saving composite prefabricated brick

Abstract

This invention belongs to the field of refractory materials technology, and particularly relates to a green and energy-saving composite precast brick. This invention provides a green and energy-saving composite precast brick that, through the combination of an outer insulation layer formed by the curing of lightweight castable and an inner wear-resistant layer formed by the curing of heavy castable, achieves the following: 1. The room-temperature wear resistance (wear-resistant layer) of this precast brick can be reduced to 3.2 cm. 3 1. The thermal conductivity (thickness direction) of the precast brick can be reduced to 0.20 W·m. ‑1 ·K ‑1 3. The overall thermodynamic properties of the precast bricks are sufficient for use in parts such as the tertiary air duct of a cement rotary kiln.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and in particular relates to a green and energy-saving composite precast brick. Background Technology

[0002] In the new dry process cement production technology, the cement rotary kiln is the most important production equipment, mainly used for calcining cement clinker.

[0003] In cement rotary kilns, the tertiary air ducts, including straight pipes, bends, and the straight walls of the tertiary air ducts within the tower, as well as the tertiary air valves, are characterized by high temperatures, strong material scouring, and severe corrosive effects from the alkaline components of the materials. Traditional cast-in-place refractory materials suffer frequent damage and have short lifespans in these areas, sometimes requiring kiln shutdowns for maintenance every 3-4 months, severely impacting the normal operation of the cement kiln.

[0004] Therefore, high-performance precast refractory bricks are more suitable for special parts of cement rotary kilns operating under harsh conditions. Generally, compared with cast-in-place refractory materials, precast bricks already have many advantages such as modular installation, convenient construction, no limitation by site environment or seasonal conditions, and no need for curing.

[0005] On the other hand, high-performance refractory precast bricks have the following advantages compared with ordinary refractory precast bricks: high strength, high temperature resistance, wear resistance, no cracking, and outstanding erosion resistance. The average service life of existing high-performance refractory precast bricks in the aforementioned special locations can even reach 3 years.

[0006] For example, Chinese invention patent CN107188579A, published on September 22, 2017, discloses a wear-resistant precast brick, which, by mass fraction, includes: 20-35 parts mullite; 3-8 parts zirconium silicate; 8-15 parts corundum powder; 15-30 parts andalusite powder; 5-10 parts sillimanite powder; 3-8 parts silica powder; 3-6 parts alumina powder; 3-7 parts calcium aluminate cement; 0.5-2 parts heat-resistant steel fiber; 0.16-0.2 parts sodium hexametaphosphate; and 0.18-0.21 parts explosion-proof fiber.

[0007] The wear-resistant precast bricks in this invention patent are used on the inner wall of an internally heated rotary kiln. They have excellent wear resistance, overcome the shortcomings of the material, and extend the replacement cycle of the cement kiln.

[0008] However, in actual use, this wear-resistant precast brick still has at least the following two shortcomings, which are also the technical problems that this invention aims to solve:

[0009] First, its wear resistance at room temperature is 3.6cm. 3The wear resistance is relatively good, but in very special parts such as the tertiary air duct of cement rotary kilns, its wear resistance is still insufficient. Generally, it can only extend the replacement cycle of the above 3-4 months to about 1 year.

[0010] Secondly, its thermal conductivity is 0.25 W·m. -1 ·K -1 Therefore, the thermal insulation performance of this precast brick is relatively average, and it cannot better save heat in the rotary kiln.

[0011] Therefore, in summary, there is an urgent need for a new type of refractory precast brick product with sufficient basic mechanical properties, outstanding wear resistance, and excellent thermal insulation properties. Summary of the Invention

[0012] This invention provides a green and energy-saving composite precast brick, which, through the combination of an outer insulation layer formed by the curing of lightweight castable and an inner wear-resistant layer formed by the curing of heavyweight castable, achieves the following: 1. The room-temperature wear resistance (wear-resistant layer) of this precast brick can be reduced to 3.2 cm. 3 1. The thermal conductivity (thickness direction) of the precast brick can be reduced to 0.20 W·m. -1 ·K -1 3. The overall thermodynamic properties of the precast bricks are sufficient for use in parts such as the tertiary air duct of a cement rotary kiln.

[0013] The technical solution adopted by the present invention to solve the above problems is: a green and energy-saving composite precast brick, the layered structure of which includes: a heat insulation layer facing the kiln wall and a wear-resistant layer facing the material, wherein the heat insulation layer is formed by curing lightweight castable and the wear-resistant layer is formed by curing heavy castable.

[0014] In this invention, when the precast brick is used, the insulation layer faces outward and the wear-resistant layer faces inward. The outstanding feature of the lightweight castable is its superior insulation performance, that is, its relatively low thermal conductivity. The outstanding feature of the heavy castable is its superior wear resistance, which ensures that it can be used stably for 2-3 years under the impact of high temperature, high alkalinity, and high flow rate materials in the tertiary air duct.

[0015] A further preferred technical solution is that: the heat insulation layer and the wear-resistant layer together form a transition zone, and the color difference value ΔE between the transition zone and the heat insulation layer and the wear-resistant layer is ≥1.2.

[0016] In this invention, the non-transition area of ​​the insulation layer is yellowish-brown, and the non-transition area of ​​the wear-resistant layer is brown. The former is relatively lighter in color, the latter is relatively darker, and the color of the transition area is between the two.

[0017] The color difference value ΔE can be directly measured using an existing colorimeter.

[0018] A further preferred technical solution is that the thickness of the transition zone is 4-15% of the thickness of the precast brick.

[0019] In this invention, the precast brick has a consistent cross-sectional shape and size in the thickness direction, that is, in the inner and outer directions when in use, and in the direction perpendicular to the thickness direction.

[0020] The method for determining the upper and lower boundaries of the transition zone includes the following steps in sequence:

[0021] T1. Select a rectangular surface with the largest dimension that is parallel to the thickness direction of the precast brick;

[0022] T2. Divide the vertical thickness direction side of the rectangular surface into n equal parts to obtain (n-1) color measurement lines;

[0023] T3. Starting from the wear-resistant layer boundary of the above color measurement line, determine a measurement point every 0.5cm to obtain multiple measurement points;

[0024] T4. Using the average color data of the first (boundary point) and the second measurement point as a reference, until the average color data of two adjacent measurement points is measured, the color difference value ΔE between the two measurement points and the above reference is ≥1.2. The midpoint between these two measurement points is the boundary point of the transition zone on the measurement line.

[0025] T5. Repeat the above method (n-2) times to find another (n-2) transition zone boundary points;

[0026] T6. Determine a centrally located equidistant line from the above (n-1) transition zone boundary points (the positive and negative distances from all points to this line are 0), which is the boundary of the transition zone near the wear-resistant layer.

[0027] T7. Change the boundary in T3 above to start from the boundary of the insulation layer and determine a measurement point every 0.2cm. Using the same method, finally determine the boundary of the transition zone on the side closer to the insulation layer, and then set it as the two sides of the entire transition zone. The remaining rectangular surfaces parallel to the thickness direction will no longer be detected, where n≥4.

[0028] On the other hand, if the ratio of the thickness of the transition zone to the thickness of the precast brick is less than 4%, it indicates that the bonding strength between the insulation layer and the wear-resistant layer is insufficient. This is ultimately reflected in the flexural strength and compressive strength (on the wear-resistant layer side) of the precast brick, which are low and have insufficient mechanical properties.

[0029] If the above ratio is greater than 15%, it indicates that the fluidity of the lightweight castable and / or heavy castable is too high, or the preparation method is inappropriate. This is ultimately reflected in the "linear changes in length and width after firing at 1100℃" parameter of the precast bricks, which is a larger value. The precast bricks are prone to mutual compression and breakage and separation gaps on the wall of the tertiary air duct.

[0030] A further preferred technical solution is that the raw material composition of the lightweight castable includes: microporous lightweight mullite, ceramsite, perlite, silica fume, and clay; the raw material composition of the heavy castable includes: mullite, grade I bauxite, silicon carbide, composite silicon micro powder, α-Al2O3 micro powder, and explosion-proof fiber.

[0031] In this invention, the ceramsite, perlite, and clay components in the lightweight castable can significantly improve its thermal insulation performance, while the mullite, silicon carbide, composite silicon micro powder, and α-Al2O3 micro powder in the heavy castable can improve the high temperature resistance, erosion resistance, corrosion resistance, and thermal shock resistance of the wear-resistant layer.

[0032] A further preferred technical solution is that the raw material composition of the lightweight castable includes the following components by weight: 35-38% microporous lightweight mullite, 23-29% ceramsite, 11-15% perlite, 2-8% silica fume, and 13-17% clay, with the balance being admixtures and water.

[0033] A further preferred technical solution is that the raw material composition of the heavy castable includes the following components by weight: 40-44% mullite, 21-28% grade 1 bauxite, 5-6% silicon carbide, 4-8% composite silicon micro powder, 13-16% α-Al2O3 micro powder, and 0.1-0.2% explosion-proof fiber, with the balance being additives and water.

[0034] A further preferred technical solution is that the microporous lightweight mullite has a particle size of 0.2-0.5 mm and an open porosity of ≥40%, and the mullite has a particle size of 0.8-1.2 mm.

[0035] A further preferred technical solution is that the admixture is any one or a mixture of several of the following: water-reducing agent, retarder, high-efficiency dispersant, and antioxidant.

[0036] In this invention, the water-reducing agent is a polycarboxylate water-reducing agent, the retarder is any one of citric acid, tartaric acid, and phosphoric acid, the high-efficiency dispersant is any one of polyacrylonitrile and carboxymethyl acrylamide, and the antioxidant is any one of aluminum powder and magnesium powder.

[0037] A further preferred technical solution is that the preparation method of the precast bricks includes the following steps in sequence:

[0038] S1. Mixing: The lightweight castable and the heavy castable are prepared by stirring and mixing separately;

[0039] S2. First casting and curing: Add the heavy casting material to the mold, and after hardening, demold and then cure to obtain a wear-resistant block;

[0040] S3. Second casting and curing: The wear-resistant block is placed back into the mold, and then the lightweight castable is added. After hardening, it is demolded and then cured to obtain a composite block.

[0041] S4. Drying: The composite block is dried with the heavy castable on top and the light castable on the bottom, and then naturally cooled to room temperature to obtain a brick blank.

[0042] S5. Firing: The brick blanks are fired, kept warm, and naturally cooled in sequence with the heavy castable on top and the light castable on the bottom to obtain the final precast brick product.

[0043] In S4 and S5 of the present invention, if the heavy castable is at the bottom and the light castable is at the top, the transition zone thickness is likely to be insufficient, which will ultimately reduce the overall mechanical properties of the precast brick.

[0044] A further preferred technical solution is as follows: in S4, the drying operation temperature is 110-130℃ and the time is ≥24h; in S5, the firing operation temperature is ≥1150℃ and the time is 1-2h; in S5, the heat preservation operation temperature is ≥800℃ and the time is ≥3h. Attached Figure Description

[0045] Figure 1 This represents the average performance test results of the precast brick samples in four embodiments of the present invention.

[0046] Figure 2 This represents the average performance test results of the precast brick samples in the six comparative examples of this invention.

[0047] Figure 3 This is a schematic diagram showing the location and shape of the transition region in this invention.

[0048] Figure 4 This is a schematic diagram of one structure of the precast brick in this invention.

[0049] Figure 5 This is a schematic diagram of another structure of the precast brick in this invention.

[0050] Figure 6 This is a schematic diagram showing the distribution of measurement points in this invention.

[0051] The meanings of the markings in the diagram are as follows:

[0052] Insulation layer a, wear-resistant layer b, transition zone c, measuring point d, color measuring line e. Detailed Implementation

[0053] The following description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

[0054] Example 1

[0055] A green and energy-saving composite precast brick has a layered structure comprising: an insulation layer a facing the kiln wall and a wear-resistant layer b facing the material, wherein the insulation layer a is formed by curing lightweight castable and the wear-resistant layer b is formed by curing heavy castable.

[0056] The insulation layer a and the wear-resistant layer b together form a transition zone c, and the color difference value ΔE between the transition zone c and the insulation layer a and the wear-resistant layer b is ≥1.2.

[0057] The thickness of the transition zone c is 5-10% of the thickness of the precast brick.

[0058] The lightweight castable refractory comprises the following components by weight:

[0059] The composition consists of 36% microporous lightweight mullite, 24% ceramsite, 11% perlite, 4% silica fume, 14% clay, 2% additives, and 9% water.

[0060] The raw material composition of the heavy castable includes the following components by weight:

[0061] The composition consists of 40% mullite, 25% grade bauxite, 5% silicon carbide, 8% composite silica powder, 13% α-Al2O3 powder, 0.2% explosion-proof fiber, 1% additives, and 7.8% water.

[0062] The microporous lightweight mullite has a particle size of 0.2-0.4 mm and an open porosity of ≥40%, the mullite has a particle size of 0.9-1.1 mm, and the explosion-proof fiber is polypropylene fiber.

[0063] The additive is a mixture of polycarboxylate superplasticizer, citric acid, tartaric acid, polyacrylonitrile, and aluminum powder.

[0064] Furthermore, the preparation method of this green and energy-saving composite precast brick includes the following steps in sequence:

[0065] S1. Mixing: The lightweight castable and the heavy castable are prepared by stirring and mixing separately;

[0066] S2. First casting and curing: Add the heavy casting material to the mold, and after hardening, demold and then cure to obtain a wear-resistant block;

[0067] S3. Second casting and curing: The wear-resistant block is placed back into the mold, and then the lightweight castable is added. After hardening, it is demolded and then cured to obtain a composite block.

[0068] S4. Drying: The composite block is dried with the heavy castable on top and the light castable on the bottom, and then naturally cooled to room temperature to obtain a brick blank.

[0069] S5. Firing: The brick blanks are fired, kept warm, and naturally cooled in sequence with the heavy castable on top and the light castable on the bottom to obtain the final precast brick product.

[0070] In S2 and S3, the temperature for both maintenance operations is 28℃ and the time is 40 hours.

[0071] In S2 and S3, the thickness of the heavy castable is 9.5 cm, and the thickness of the lightweight castable is 3.5 cm. These absolute values ​​and relative proportions are not relevant parameters for the wear-resistant layer b and the insulation layer a in the final precast brick product, because precast bricks undergo relatively significant changes in shape and size during drying and firing.

[0072] In S4, the drying operation is performed at a temperature of 110°C for a time of 30 hours.

[0073] In S5, the firing temperature is 1150℃ and the time is 2h; in S5, the heat preservation temperature is 800℃ and the time is 6h.

[0074] Finally, taking 50 of the aforementioned composite precast bricks from this embodiment, and based on existing performance testing standards for refractory precast bricks, [the following is a list of bricks / bricks]. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 1 In the table.

[0075] Example 2

[0076] A green and energy-saving composite precast brick has a layered structure comprising: an insulation layer a facing the kiln wall and a wear-resistant layer b facing the material, wherein the insulation layer a is formed by curing lightweight castable and the wear-resistant layer b is formed by curing heavy castable.

[0077] The insulation layer a and the wear-resistant layer b together form a transition zone c, and the color difference value ΔE between the transition zone c and the insulation layer a and the wear-resistant layer b is ≥1.2.

[0078] The thickness of the transition zone c is 6-9% of the thickness of the precast brick.

[0079] The lightweight castable refractory comprises the following components by weight:

[0080] The composition consists of 37% microporous lightweight mullite, 23% ceramsite, 11% perlite, 5% silica fume, 13% clay, 1% additives, and 10% water.

[0081] The raw material composition of the heavy castable includes the following components by weight:

[0082] The composition consists of 42% mullite, 23% grade bauxite, 6% silicon carbide, 7% composite silica powder, 13% α-Al2O3 powder, 0.2% explosion-proof fiber, 1% additives, and 7.8% water.

[0083] The microporous lightweight mullite has a particle size of 0.2-0.4 mm and an open porosity of ≥40%, the mullite has a particle size of 1.0-1.2 mm, and the explosion-proof fiber is polypropylene fiber.

[0084] The additive is a mixture of polycarboxylate superplasticizer, citric acid, tartaric acid, polyacrylonitrile, and aluminum powder.

[0085] Furthermore, the preparation method of this green and energy-saving composite precast brick includes the following steps in sequence:

[0086] S1. Mixing: The lightweight castable and the heavy castable are prepared by stirring and mixing separately;

[0087] S2. First casting and curing: Add the heavy casting material to the mold, and after hardening, demold and then cure to obtain a wear-resistant block;

[0088] S3. Second casting and curing: The wear-resistant block is placed back into the mold, and then the lightweight castable is added. After hardening, it is demolded and then cured to obtain a composite block.

[0089] S4. Drying: The composite block is dried with the heavy castable on top and the light castable on the bottom, and then naturally cooled to room temperature to obtain a brick blank.

[0090] S5. Firing: The brick blanks are fired, kept warm, and naturally cooled in sequence with the heavy castable on top and the light castable on the bottom to obtain the final precast brick product.

[0091] In S2 and S3, the temperature for both maintenance operations is 25℃ and the time is 40 hours.

[0092] In S2 and S3, the thickness of the heavy castable is 9.5 cm, and the thickness of the lightweight castable is 3.5 cm. These absolute values ​​and relative proportions are not relevant parameters for the wear-resistant layer b and the insulation layer a in the final precast brick product, because precast bricks undergo relatively significant changes in shape and size during drying and firing.

[0093] In S4, the drying operation is performed at a temperature of 120°C for 24 hours.

[0094] In S5, the firing temperature is 1200℃ and the time is 2h; in S5, the heat preservation temperature is 800℃ and the time is 5h.

[0095] Finally, taking 50 of the aforementioned composite precast bricks from this embodiment, and based on existing performance testing standards for refractory precast bricks, [the following is a list of bricks / bricks]. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 1 In the table.

[0096] Example 3

[0097] A green and energy-saving composite precast brick has a layered structure comprising: an insulation layer a facing the kiln wall and a wear-resistant layer b facing the material, wherein the insulation layer a is formed by curing lightweight castable and the wear-resistant layer b is formed by curing heavy castable.

[0098] The insulation layer a and the wear-resistant layer b together form a transition zone c, and the color difference value ΔE between the transition zone c and the insulation layer a and the wear-resistant layer b is ≥1.2.

[0099] The thickness of the transition zone c is 7-9% of the thickness of the precast brick.

[0100] The lightweight castable refractory comprises the following components by weight:

[0101] The composition consists of 36% microporous lightweight mullite, 25% ceramsite, 11% perlite, 3% silica fume, 14% clay, 1% additives, and 10% water.

[0102] The raw material composition of the heavy castable includes the following components by weight:

[0103] The composition consists of 44% mullite, 23% grade bauxite, 5% silicon carbide, 6% composite silica powder, 13% α-Al2O3 powder, 0.2% explosion-proof fiber, 2% additives, and 6.8% water.

[0104] The microporous lightweight mullite has a particle size of 0.2-0.5 mm and an open porosity of ≥40%, the mullite has a particle size of 0.8-1.2 mm, and the explosion-proof fiber is polypropylene fiber.

[0105] The additive is a mixture of polycarboxylate superplasticizer, citric acid, tartaric acid, polyacrylonitrile, and aluminum powder.

[0106] Furthermore, the preparation method of this green and energy-saving composite precast brick includes the following steps in sequence:

[0107] S1. Mixing: The lightweight castable and the heavy castable are prepared by stirring and mixing separately;

[0108] S2. First casting and curing: Add the heavy casting material to the mold, and after hardening, demold and then cure to obtain a wear-resistant block;

[0109] S3. Second casting and curing: The wear-resistant block is placed back into the mold, and then the lightweight castable is added. After hardening, it is demolded and then cured to obtain a composite block.

[0110] S4. Drying: The composite block is dried with the heavy castable on top and the light castable on the bottom, and then naturally cooled to room temperature to obtain a brick blank.

[0111] S5. Firing: The brick blanks are fired, kept warm, and naturally cooled in sequence with the heavy castable on top and the light castable on the bottom to obtain the final precast brick product.

[0112] In S2 and S3, the temperature for both maintenance operations is 25℃ and the time is 25h.

[0113] In S2 and S3, the thickness of the heavy castable is 9.5 cm, and the thickness of the lightweight castable is 3.5 cm. These absolute values ​​and relative proportions are not relevant parameters for the wear-resistant layer b and the insulation layer a in the final precast brick product, because precast bricks undergo relatively significant changes in shape and size during drying and firing.

[0114] In S4, the drying operation is performed at a temperature of 130°C for 24 hours.

[0115] In S5, the firing temperature is 1200℃ and the time is 1h; in S5, the heat preservation temperature is 1000℃ and the time is 5h.

[0116] Finally, taking 50 of the aforementioned composite precast bricks from this embodiment, and based on existing performance testing standards for refractory precast bricks, [the following is a list of bricks / bricks]. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 1 In the table.

[0117] Example 4

[0118] A green and energy-saving composite precast brick has a layered structure comprising: an insulation layer a facing the kiln wall and a wear-resistant layer b facing the material, wherein the insulation layer a is formed by curing lightweight castable and the wear-resistant layer b is formed by curing heavy castable.

[0119] The insulation layer a and the wear-resistant layer b together form a transition zone c, and the color difference value ΔE between the transition zone c and the insulation layer a and the wear-resistant layer b is ≥1.2.

[0120] The thickness of the transition zone c is 5-6% of the thickness of the precast brick.

[0121] The lightweight castable refractory comprises the following components by weight:

[0122] The composition consists of 35% microporous lightweight mullite, 24% ceramsite, 11% perlite, 5% silica fume, 13% clay, 1% additives, and 11% water.

[0123] The raw material composition of the heavy castable includes the following components by weight:

[0124] The composition consists of 43% mullite, 23% grade bauxite, 5% silicon carbide, 7% composite silica powder, 13% α-Al2O3 powder, 0.2% explosion-proof fiber, 1% additives, and 7.8% water.

[0125] The microporous lightweight mullite has a particle size of 0.3-0.5 mm and an open porosity of ≥40%, the mullite has a particle size of 0.8-1.1 mm, and the explosion-proof fiber is polypropylene fiber.

[0126] The additive is a mixture of polycarboxylate superplasticizer, citric acid, tartaric acid, polyacrylonitrile, and aluminum powder.

[0127] Furthermore, the preparation method of this green and energy-saving composite precast brick includes the following steps in sequence:

[0128] S1. Mixing: The lightweight castable and the heavy castable are prepared by stirring and mixing separately;

[0129] S2. First casting and curing: Add the heavy casting material to the mold, and after hardening, demold and then cure to obtain a wear-resistant block;

[0130] S3. Second casting and curing: The wear-resistant block is placed back into the mold, and then the lightweight castable is added. After hardening, it is demolded and then cured to obtain a composite block.

[0131] S4. Drying: The composite block is dried with the heavy castable on top and the light castable on the bottom, and then naturally cooled to room temperature to obtain a brick blank.

[0132] S5. Firing: The brick blanks are fired, kept warm, and naturally cooled in sequence with the heavy castable on top and the light castable on the bottom to obtain the final precast brick product.

[0133] In S2 and S3, the temperature for both maintenance operations is 25℃ and the time is 25h.

[0134] In S2 and S3, the thickness of the heavy castable is 9.5 cm, and the thickness of the lightweight castable is 3.5 cm. These absolute values ​​and relative proportions are not relevant parameters for the wear-resistant layer b and the insulation layer a in the final precast brick product, because precast bricks undergo relatively significant changes in shape and size during drying and firing.

[0135] In S4, the drying operation is performed at a temperature of 130°C for a time of 35 hours.

[0136] In S5, the firing temperature is 1300℃ and the time is 1h; in S5, the heat preservation temperature is 800℃ and the time is 3h.

[0137] Finally, taking 50 of the aforementioned composite precast bricks from this embodiment, and based on existing performance testing standards for refractory precast bricks, [the following is a list of bricks / bricks]. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 1 In the table.

[0138] Comparative Example 1

[0139] The green and energy-saving composite precast bricks in this comparative example differ from those in Example 1 in only one aspect, namely, in terms of raw material formulation and preparation method:

[0140] The insulation layer a is also formed by curing heavy castable.

[0141] Finally, taking 50 of the aforementioned composite precast bricks from the same comparative example, and based on existing performance testing standards for refractory precast bricks, the results are attached. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 2 In the table.

[0142] Comparative Example 2

[0143] The green and energy-saving composite precast bricks in this comparative example differ from those in Example 1 in only one aspect, namely, in terms of raw material formulation and preparation method:

[0144] The wear-resistant layer b is also formed by curing a lightweight castable.

[0145] Finally, taking 50 of the aforementioned composite precast bricks from the same comparative example, and based on existing performance testing standards for refractory precast bricks, the results are attached. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 2 In the table.

[0146] Comparative Example 3

[0147] The green and energy-saving composite precast bricks in this comparative example differ from those in Example 1 in only one aspect, namely, in terms of raw material formulation and preparation method:

[0148] The insulation layer a is formed by curing heavy castable, and the wear-resistant layer b is formed by curing light castable; the raw materials of the two are interchangeable.

[0149] Finally, taking 50 of the aforementioned composite precast bricks from the same comparative example, and based on existing performance testing standards for refractory precast bricks, the results are attached. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 2 In the table.

[0150] Comparative Example 4

[0151] The green and energy-saving composite precast bricks in this comparative example differ from those in Example 1 in only one aspect, namely, in terms of raw material formulation and preparation method:

[0152] In S2 and S3, the casting thickness of the heavy castable is 6.5 cm, and the casting thickness of the lightweight castable is also 6.5 cm.

[0153] Finally, taking 50 of the aforementioned composite precast bricks from the same comparative example, and based on existing performance testing standards for refractory precast bricks, the results are attached. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 2 In the table.

[0154] Comparative Example 5

[0155] The green and energy-saving composite precast bricks in this comparative example differ from those in Example 1 in only one aspect, namely, in terms of raw material formulation and preparation method:

[0156] In S4 and S5, the heavy castable is at the bottom and the light castable is at the top. The positions of the two are interchanged, and the thickness of the transition zone c is 2-3% of the thickness of the precast brick.

[0157] Finally, taking 50 of the aforementioned composite precast bricks from the same comparative example, and based on existing performance testing standards for refractory precast bricks, the results are attached. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 2 In the table.

[0158] Comparative Example 6

[0159] The green and energy-saving composite precast bricks in this comparative example differ from those in Example 1 in only one aspect, namely, in terms of raw material formulation and preparation method:

[0160] In S4, the drying operation temperature is 50℃ and the time is 150h, and the thickness of the transition zone c is 20-22% of the thickness of the precast brick.

[0161] Finally, taking 50 of the aforementioned composite precast bricks from the same comparative example, and based on existing performance testing standards for refractory precast bricks, the results are attached. Figure 1 Eight performance indicators were tested, the average value was taken, and the results were recorded in the appendix. Figure 2 In the table.

[0162] Summary and Analysis

[0163] The composite precast bricks in the first and fourth embodiments all have the following outstanding comprehensive advantages: room temperature wear resistance of 3.1cm. 3 Left and right, thermal conductivity 0.20 W·m -1 ·K -1 With relatively high thermal and mechanical properties, it can guarantee an effective service life of 2-3 years when used in special parts such as tertiary air ducts.

[0164] Secondly, the overall performance of the composite precast bricks in the six comparative examples was not as good as that of the example, proving that the characteristics of the precast brick corresponding to their respective "single variables" are necessary for the overall performance of the precast brick.

[0165] Third, among the six comparative examples, Comparative Example 3 had the worst overall performance, with its wear resistance and thermo / mechanical properties significantly reduced compared to the examples.

[0166] Fourth, regarding the parameter of "linear change after firing at 1100℃ (%)", only Comparative Example 6 showed a significant performance reduction. The direct cause is that the ratio of the thickness of the transition zone c to the thickness of the precast brick is too high. The root cause may be that the excessive doping of the insulation layer a and the wear-resistant layer b allows materials that are relatively prone to thermal deformation, such as primary bauxite and perlite, to be distributed over a larger area, ultimately increasing the linear change rate and making it unfavorable for the orderly splicing of precast bricks.

[0167] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various modifications can be made without departing from the spirit of the present invention. These are non-inventive modifications and are protected by patent law as long as they fall within the scope of the claims of the present invention.

Claims

1. A green and energy-saving composite precast brick, characterized in that... The layered structure includes: an insulation layer (a) facing the kiln wall, and a wear-resistant layer (b) facing the material, wherein the insulation layer (a) is formed by curing a lightweight castable, and the wear-resistant layer (b) is formed by curing a heavyweight castable. The insulation layer (a) and the wear-resistant layer (b) together form a transition zone (c), and the color difference value ΔE between the transition zone (c) and the insulation layer (a) and the wear-resistant layer (b) is ≥1.

2. The thickness of the transition zone (c) is 4-15% of the thickness of the precast bricks. The method for determining the upper and lower boundaries of the transition zone (c) includes the following steps in sequence: T1. Select a rectangular surface with the largest dimension that is parallel to the thickness direction of the precast brick; T2. Divide the vertical thickness direction side of the rectangular surface into n equal parts to obtain (n-1) color measurement lines (e). T3. Starting from the wear-resistant layer boundary of the color measurement line (e), determine a measurement point (d) every 0.5cm to obtain a number of measurement points (d). T4. Using the average color data of the first boundary point and the second measurement point (d) as a reference, until the average color data of two adjacent measurement points (d) is measured, the color difference value ΔE between the reference and the reference is ≥1.

2. The midpoint between these two measurement points is taken as the boundary point of the transition zone on the color measurement line (e). Repeat steps T5 and T1-T4 (n-2) times to find another (n-2) transition zone boundary points; T6. A centrally located equidistant line is determined by a total of (n-1) transition zone boundary points. The sum of the positive and negative distances from all transition zone boundary points to the equidistant line is 0. The equidistant line is the boundary of the transition zone (c) on the side closer to the wear-resistant layer (b). T7. Change the boundary in T3 to start from the boundary of the insulation layer, and determine a measurement point (d) every 0.2cm. Using the same method, finally determine the boundary of the transition zone (c) on the side closer to the insulation layer (a), and then set it as the two side boundaries of the entire transition zone (c). The remaining rectangular surfaces parallel to the thickness direction will no longer be detected, where n≥4. The method for preparing the precast bricks includes the following steps in sequence: S1. Mixing: The lightweight castable and the heavy castable are prepared by stirring and mixing separately; S2. First casting and curing: Add the heavy casting material to the mold, and after hardening, demold and then cure to obtain a wear-resistant block; S3. Second casting and curing: The wear-resistant block is placed back into the mold, and then the lightweight castable is added. After hardening, it is demolded and then cured to obtain a composite block. S4. Drying: The composite block is dried with the heavy castable on top and the light castable on the bottom, and then naturally cooled to room temperature to obtain a brick blank. S5. Firing: The brick blanks are fired, heat-preserved, and naturally cooled sequentially with the heavy castable on top and the light castable on the bottom to obtain the final precast brick product. In S4, the drying operation is performed at a temperature of 110-130℃ for a time of ≥24h; in S5, the firing operation is performed at a temperature of ≥1150℃ for a time of 1-2h; in S5, the heat preservation operation is performed at a temperature of ≥800℃ for a time of ≥3h.

2. The green and energy-saving composite precast brick according to claim 1, characterized in that... The raw material composition of the lightweight castable includes: microporous lightweight mullite, ceramsite, perlite, silica fume, and clay; the raw material composition of the heavy castable includes: mullite, grade I bauxite, silicon carbide, composite silicon micro powder, α-Al2O3 micro powder, and explosion-proof fiber.

3. The green and energy-saving composite precast brick according to claim 2, characterized in that... The raw material composition of the lightweight castable includes the following components by weight: 35-38% microporous lightweight mullite, 23-29% ceramsite, 11-15% perlite, 2-8% silica fume, and 13-17% clay, with the balance being admixtures and water.

4. The green and energy-saving composite precast brick according to claim 2, characterized in that... The raw material composition of the heavy castable includes the following components by weight: Mullite 40-44%, Grade I bauxite 21-28%, silicon carbide 5-6%, composite silicon micro powder 4-8%, α-Al2O3 micro powder 13-16%, and explosion-proof fiber 0.1-0.2%, with the balance being additives and water.

5. The green and energy-saving composite precast brick according to claim 2, characterized in that: The microporous lightweight mullite has a particle size of 0.2-0.5 mm and an open porosity of ≥40%, and the mullite has a particle size of 0.8-1.2 mm.

6. A green and energy-saving composite precast brick according to claim 3 or 4, characterized in that: The admixture is any one or a mixture of several of the following: water-reducing agent, retarder, high-efficiency dispersant, and antioxidant.

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