Composite heat-insulating brick for rotary kiln lining and preparation method of composite heat-insulating brick
By adding specific raw materials to the insulation base layer and lightweight refractory layer of the composite insulation bricks, composite insulation bricks with gradient structures are formed, which solves the problem that traditional insulation bricks are prone to cracks under temperature fluctuations, and achieves higher thermal shock resistance and service life.
Patent Information
- Application Number
- CN202510193375.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-20
- Publication Date
- 2025-05-27
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The thermal insulation bricks used in traditional rotary kiln linings may cause thermal shock under frequent temperature fluctuations, resulting in cracks, which will reduce performance and service life.
Composite thermal insulation bricks are used, which include a thermal insulation base layer, a lightweight refractory layer and a connecting column. By adding polyacrylamide and silicon carbide whiskers to the thermal insulation base layer, carbon fibers and cerium oxide are added to the lightweight refractory layer to form composite thermal insulation bricks with a gradient structure to reduce crack generation.
It improves the elastic modulus and hardness of the brick body, reduces porosity, enhances thermal shock resistance, extends service life, and improves the overall mechanical strength and thermal insulation effect of the kiln lining.
Smart Images
Figure CN120040195A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of composite heat-insulating bricks for rotary kiln linings, and specifically to a composite heat-insulating brick for rotary kiln linings and a preparation method thereof. Background Art
[0002] The heat-insulating brick for the rotary kiln lining is a material that plays a key role in the stable operation and energy conservation of the rotary kiln. It is mainly made of lightweight heat-insulating raw materials such as diatomite, ceramic fiber, and cenospheres, and is formed by special processing techniques. These raw materials themselves have extremely low thermal conductivity, which can greatly prevent the heat in the kiln from dissipating to the outside of the kiln, thereby reducing energy consumption and improving the thermal efficiency of the rotary kiln. The unique porous structure inside is the key to its excellent heat-insulating performance. These tiny and evenly distributed pores effectively block the heat conduction path. Moreover, the heat-insulating brick also has good chemical stability, can resist the erosion of complex chemical substances in the kiln, and at the same time has a certain mechanical strength, can withstand the vibration and impact during the operation of the rotary kiln, and is not easily damaged. With excellent heat-insulating, stable, and compressive properties, the heat-insulating brick is widely used in the rotary kiln linings of industries such as cement, steel, and chemical engineering, providing strong support for the efficient and energy-saving production of the industry.
[0003] During the operation of the rotary kiln, the traditional heat-insulating brick for the rotary kiln lining may experience frequent temperature fluctuations, such as starting and stopping the kiln and temperature adjustment during the production process. As a result, thermal shock will occur. Under the action of thermal shock, cracks may be generated, which will further cause problems such as a decline in the performance and service life of the heat-insulating brick. Summary of the Invention
[0004] Aiming at the deficiencies of the prior art, the present invention provides a composite heat-insulating brick for rotary kiln linings and a preparation method thereof, which solve the problems that during the operation of the rotary kiln, the traditional heat-insulating brick for the rotary kiln lining may experience frequent temperature fluctuations, such as starting and stopping the kiln and temperature adjustment during the production process. As a result, thermal shock will occur. Under the action of thermal shock, cracks may be generated, which will further cause problems such as a decline in the performance and service life of the heat-insulating brick.
[0005] To achieve the above object, the present invention is realized through the following technical solutions: a composite heat-insulating brick for a rotary kiln lining, which includes connecting columns, a lightweight refractory layer, and a heat-insulating base layer. The heat-insulating base layer includes the following raw materials in parts by weight: 10-15 parts of silica fine powder, 4-7 parts of aluminum silicate, 3-5 parts of aluminum silicate fiber, 1-3 parts of polyacrylamide, 0.5-1 part of silicon carbide whiskers, 2-3 parts of corundum powder, and 1.5-3 parts of an auxiliary agent. The lightweight refractory layer includes the following raw materials in parts by weight: 4-7 parts of cenospheres, 5-8 parts of alumina hollow spheres, 2-5 parts of zirconia hollow spheres, 5-9 parts of expanded perlite, 3-7 parts of dolomite powder, 7-12 parts of kaolin, 1-2 parts of carbon fiber, 3-4 parts of mullite powder, and 1.5-3 parts of an auxiliary agent. The connecting columns include the following raw materials in parts by weight: 2-5 parts of composite fiber, 1-3 parts of expanded vermiculite, 2-7 parts of alumina powder, 3-5 parts of magnesium oxide, 0.5-1 part of yttrium oxide, 0.5-1 part of silicon carbide whiskers, and 1-2 parts of corundum particles.
[0006] Preferably, the auxiliary agent of the heat-insulating base layer includes the following raw materials in parts by weight: 1-2 parts of alumina and 0.5-1 part of yttrium oxide. The auxiliary agent of the lightweight refractory layer includes the following raw materials in parts by weight: 1-2 parts of zirconia and 0.5-1 part of cerium oxide.
[0007] Preferably, the particle sizes of the components in the heat-insulating base layer are respectively: 40-80μm for silica fine powder, 80-120μm for aluminum silicate, 20-30μm for polyacrylamide, 60-80μm for alumina, 20-30μm for yttrium oxide, and 80-100μm for corundum powder. The length of the aluminum silicate fiber in the heat-insulating base layer is 1-2 cm.
[0008] Preferably, the particle sizes of the components in the lightweight refractory layer are respectively: 1-2 mm for cenospheres, 0.5-1 mm for alumina hollow spheres, 1-1.5 mm for zirconia hollow spheres, 1-2 mm for expanded perlite, 20-40μm for dolomite powder, 60-100μm for kaolin, 80-100μm for zirconia, 20-30μm for cerium oxide, and 80-120μm for mullite powder. The length of the carbon fiber in the lightweight refractory layer is 5-10 mm.
[0009] Preferably, the lengths of the components in the connecting columns are respectively: 2-3 cm for alumina fiber, 1-3 cm for carbon fiber, 0.5-2 cm for graphite fiber, and 10-20μm for silicon carbide whiskers. The particle sizes of the components in the connecting columns are respectively: 0.5-1.5 mm for expanded vermiculite, 60-80μm for alumina powder, 20-60μm for magnesium oxide, 20-30μm for yttrium oxide, and 1-2 mm for corundum particles.
[0010] Preferably, a lightweight refractory layer is provided on the upper part of the heat insulation base layer. Connecting columns are arranged inside the lightweight refractory layer. An installation groove is formed on the upper surface of the lightweight refractory layer, and the lightweight refractory layer is located inside the installation groove.
[0011] Preferably, the connecting columns are in an "n" shape.
[0012] A preparation method of a composite heat insulation brick for a rotary kiln lining includes the following steps:
[0013] S1. Raw material mixing:
[0014] Preparation of heat insulation base layer powder: Weigh each component of the raw materials according to the formula, then put the raw materials into a mixer for mixing. Control the rotation speed of the mixer at 80 - 100 r / min and the mixing duration at 20 - 30 min. After mixing, heat insulation base layer powder is obtained.
[0015] Preparation of lightweight refractory layer powder: Weigh each component of the raw materials according to the formula, then put the raw materials into a mixer for mixing. Control the rotation speed of the mixer at 60 - 80 r / min and the mixing duration at 40 - 60 min to obtain lightweight refractory layer powder.
[0016] Preparation of connecting column powder: Weigh each component of the raw materials according to the formula, then put the raw materials into a mixer for mixing. Control the rotation speed of the mixer at 100 - 120 r / min and the mixing duration at 5 - 10 min to obtain connecting column powder.
[0017] S2. Pressing the brick blank: Adopt the isostatic pressing method. First, pour the heat insulation base layer powder into the heat insulation base layer cavity in the mold, apply a pre-pressure of 1 - 1.5 MPa, and maintain it for 2 - 3 min. Then pour the lightweight refractory layer powder into the lightweight refractory cavity in the mold, also apply a pre-pressure of 1 - 1.5 MPa, and maintain it for 2 - 3 min. Then take out the middle partition board and press it through an isostatic press. Control the pressing pressure at 2.4 - 2.6 MPa, and the number of pressing times at 3 - 5 times. The holding time for each time is 1 - 2 min. After pressing, a composite heat insulation brick blank with a gradient structure is obtained, so that the thermal expansion coefficient of the brick body gradually changes from the heat insulation base layer to the lightweight refractory layer.
[0018] S3. Preparing the connecting columns: Put the connecting column powder into a rubber sleeve, tamp it repeatedly for 5 - 8 times, then put it into a cold isostatic press for pressing. Control the working pressure of the cold isostatic press at 8.5 - 9.3 MPa and the pressing duration at 20 - 30 min. After pressing, take out the rubber sleeve to obtain the connecting column blank.
[0019] S4. Sintering:
[0020] Brick blank sintering: Put the composite heat-insulating brick blank into a sintering furnace, heat it to 1300 - 1600 °C at a heating rate of 5 - 10 °C / min, keep it warm for 8 - 12 h, and then cool it to room temperature at a cooling rate of 3 - 5 °C / min to form a composite heat-insulating brick;
[0021] Connecting column blank sintering: Put the connecting column blank into another sintering furnace, heat it to 1500 - 1700 °C at a heating rate of 8 - 12 °C / min, keep it warm for 5 - 8 h, and then cool it to room temperature at a cooling rate of 4 - 6 °C / min.
[0022] The present invention provides a composite heat-insulating brick for a rotary kiln lining and a preparation method thereof. It has the following beneficial effects:
[0023] 1. In the present invention, by adding polyacrylamide and silicon carbide whiskers to the heat-insulating base layer, and adding carbon fiber and cerium oxide to the lightweight refractory layer, the elastic modulus and hardness of the brick body can be increased, and the porosity can be reduced at the same time. Then, the heat-insulating base layer and the lightweight refractory layer are compounded and fired to form a composite and cooperate with each other to reduce the generation of cracks, thereby improving the problem that the heat-insulating brick for the traditional rotary kiln lining may experience frequent thermal shocks caused by temperature fluctuations during the operation of the rotary kiln, and cracks may be generated under the action of thermal shocks, which may further cause the performance and service life of the heat-insulating brick to decline.
[0024] 2. In the present invention, by adding alumina and yttrium oxide to the heat-insulating base layer, and adding zirconia and cerium oxide to the lightweight refractory layer, the high-temperature stability of the heat-insulating brick can be improved, further reducing the deformation, cracking and even spalling of the brick body, thereby increasing the service life of the kiln lining.
[0025] 3. In the present invention, by adding corundum and mullite to the lightweight heat-insulating material to form a framework support structure, the overall mechanical strength of the brick body can be improved. During the operation of the rotary kiln, under the actions of the impact, friction of the materials and the vibration of the kiln body, it can ensure that the brick body is not damaged, thereby improving the integrity and heat-insulating effect of the kiln lining. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 It is a three-dimensional structure schematic diagram of the present invention;
[0027] Figure 2 It is a structure installation schematic diagram of the present invention;
[0028] Figure 3 It is a preparation process flow chart of the present invention.
[0029] Among them, 1. Connecting column; 2. Lightweight refractory layer; 3. Heat-insulating base layer; 4. Installation groove. DETAILED DESCRIPTION OF THE INVENTION
[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0031] Please refer to the attached Figure 1 - attached Figure 2 , the present invention provides a composite heat-insulating brick for a rotary kiln lining, which includes a connecting column 1, a light refractory layer 2, and a heat-insulating base layer 3. The heat-insulating base layer 3 includes the following raw materials in parts by weight: 10-15 parts of silica fine powder, 4-7 parts of aluminum silicate, 3-5 parts of aluminum silicate fiber, 1-3 parts of polyacrylamide, 0.5-1 part of silicon carbide whiskers, 2-3 parts of corundum powder, and 1.5-3 parts of an auxiliary agent. The light refractory layer 2 includes the following raw materials in parts by weight: 4-7 parts of cenospheres, 5-8 parts of alumina hollow spheres, 2-5 parts of zirconia hollow spheres, 5-9 parts of expanded perlite, 3-7 parts of dolomite powder, 7-12 parts of kaolin, 1-2 parts of carbon fiber, 3-4 parts of mullite powder, and 1.5-3 parts of an auxiliary agent. The connecting column 1 includes the following raw materials in parts by weight: 2-5 parts of composite fiber, 1-3 parts of expanded vermiculite, 2-7 parts of alumina powder, 3-5 parts of magnesium oxide, 0.5-1 part of yttrium oxide, 0.5-1 part of silicon carbide whiskers, and 1-2 parts of corundum particles.
[0032] The auxiliary agent of the heat-insulating base layer 3 includes the following raw materials in parts by weight: 1-2 parts of alumina and 0.5-1 part of yttrium oxide. The auxiliary agent of the light refractory layer 2 includes the following raw materials in parts by weight: 1-2 parts of zirconia and 0.5-1 part of cerium oxide.
[0033] The particle sizes of the components in the heat-insulating base layer 3 are respectively: 40-80 μm for silica fine powder, 80-120 μm for aluminum silicate, 20-30 μm for polyacrylamide, 60-80 μm for alumina, 20-30 μm for yttrium oxide, and 80-100 μm for corundum powder. The length of the aluminum silicate fiber in the heat-insulating base layer 3 is 1-2 cm.
[0034] The particle sizes of the components in the light refractory layer 2 are respectively: 1-2 mm for cenospheres, 0.5-1 mm for alumina hollow spheres, 1-1.5 mm for zirconia hollow spheres, 1-2 mm for expanded perlite, 20-40 μm for dolomite powder, 60-100 μm for kaolin, 80-100 μm for zirconia, 20-30 μm for cerium oxide, and 80-120 μm for mullite powder. The length of the carbon fiber in the light refractory layer 2 is 5-10 mm.
[0035] The lengths of the components in the connecting column 1 are 2 - 3 cm for alumina fibers, 1 - 3 cm for carbon fibers, 0.5 - 2 cm for graphite fibers, and 10 - 20 μm for silicon carbide whiskers. The particle sizes of the components in the connecting column 1 are 0.5 - 1.5 mm for expanded vermiculite, 60 - 80 μm for alumina powder, 20 - 60 μm for magnesia, 20 - 30 μm for yttrium oxide, and 1 - 2 mm for corundum particles.
[0036] Please refer to the appendix Figure 1 - appendix Figure 2 On the upper part of the heat insulation base layer 3, there is a lightweight refractory layer 2. Inside the lightweight refractory layer 2, there is a connecting column 1. An installation groove 4 is opened on the upper surface of the lightweight refractory layer 2. The lightweight refractory layer 2 is located inside the installation groove 4. The connecting column 1 is in an n - shape.
[0037] Specifically, the heat insulation base layer 3 can effectively prevent heat from conducting from the high - temperature area inside the kiln to the outside of the kiln body, reduce heat loss, thereby improving the thermal efficiency of the rotary kiln and reducing energy consumption. And it can withstand a certain amount of pressure and stress, ensuring that the insulation bricks will not easily deform or be damaged during use, and thus maintaining the integrity of the entire kiln lining structure. Through the polyacrylamide in the heat insulation base layer 3 and substances such as added alumina, yttrium oxide, and silicon carbide whiskers, it helps to buffer and disperse thermal stress, improve the thermal shock resistance of the insulation bricks, prevent cracking or spalling caused by thermal stress, and extend the service life of the insulation bricks. The lightweight refractory layer 2 can withstand the high - temperature environment inside the rotary kiln, protect the kiln lining from high - temperature erosion, and ensure the normal operation of the rotary kiln. The materials such as expanded perlite inside have a low thermal conductivity, which can further reduce heat transfer to the outside of the kiln body and enhance the heat insulation effect of the entire composite insulation brick. Raising the dolomite level increases the refractoriness of the lightweight refractory layer 2, enabling it to remain stable at high temperatures, not easily melting or softening, thus ensuring that the kiln lining can still maintain good structure and performance under long - term high - temperature action. The carbon fibers inside can improve the toughness of the lightweight refractory layer 2, while zirconia and cerium oxide help to enhance the stability of the material, thereby improving the thermal shock resistance of the lightweight refractory layer 2. The connecting column 1 can extend into the installation groove 4. Applying ceramic binder on the outer wall of the connecting column 1 helps to fix the connecting column 1 inside the installation groove 4, and thus can connect adjacent composite insulation bricks together, improving the integrity.
[0038] Please refer to the appendix Figure 3 For the preparation method of the composite insulation brick used for the rotary kiln lining, it includes the following steps:
[0039] S1. Raw material mixing:
[0040] Preparation of the powder for the heat-insulating base layer 3: Weigh each component of the raw materials according to the formula, and then put the raw materials into a mixer for mixing. Control the rotation speed of the mixer at 80 - 100 r / min and the mixing duration at 20 - 30 min. After mixing, the powder for the heat-insulating base layer 3 is obtained;
[0041] Preparation of the powder for the lightweight refractory layer 2: Weigh each component of the raw materials according to the formula, and then put the raw materials into a mixer for mixing. Control the rotation speed of the mixer at 60 - 80 r / min and the mixing duration at 40 - 60 min to obtain the powder for the lightweight refractory layer;
[0042] Preparation of the powder for the connecting column 1: Weigh each component of the raw materials according to the formula, and then put the raw materials into a mixer for mixing. Control the rotation speed of the mixer at 100 - 120 r / min and the mixing duration at 5 - 10 min to obtain the powder for the connecting column;
[0043] S2. Pressing the brick blank: Adopt the isostatic pressing method. First, pour the powder for the heat-insulating base layer 3 into the heat-insulating base layer cavity in the mold, apply a pre-pressure of 1 - 1.5 MPa, and maintain it for 2 - 3 min; then pour the powder for the lightweight refractory layer 2 into the lightweight refractory cavity in the mold, apply the same pre-pressure of 1 - 1.5 MPa, and maintain it for 2 - 3 min. Then take out the middle partition board and press it through an isostatic press. Control the pressing pressure at 2.4 - 2.6 MPa, the number of pressing times at 3 - 5 times, and the holding time for each time at 1 - 2 min. After pressing, a composite heat-insulating brick blank with a gradient structure is obtained, making the thermal expansion coefficient of the brick body gradually change from the heat-insulating base layer 3 to the lightweight refractory layer 2;
[0044] S3. Preparing the connecting column: Put the powder for the connecting column 1 into a rubber sleeve and tamp it repeatedly for 5 - 8 times, and then put it into a cold isostatic press for pressing. Control the working pressure of the cold isostatic press at 8.5 - 9.3 MPa and the pressing duration at 20 - 30 min. After pressing, take out the rubber sleeve to obtain the connecting column blank;
[0045] S4. Sintering:
[0046] Sintering of the brick blank: Put the composite heat-insulating brick blank into a sintering furnace, raise the temperature to 1300 - 1600 °C at a heating rate of 5 - 10 °C / min, keep it warm for 8 - 12 h, and then cool it to room temperature at a cooling rate of 3 - 5 °C / min to form a composite heat-insulating brick;
[0047] Sintering of the connecting column blank: Put the connecting column blank into another sintering furnace, raise the temperature to 1500 - 1700 °C at a heating rate of 8 - 12 °C / min, keep it warm for 5 - 8 h, and then cool it to room temperature at a cooling rate of 4 - 6 °C / min.
[0048] The following is a further introduction in combination with specific embodiments:
[0049] Example 1:
[0050] In the heat-insulating base layer 3 of the composite heat-insulating brick for the rotary kiln lining, the weight parts of each raw material are 15 parts of silica fine powder, 7 parts of aluminum silicate, 5 parts of aluminum silicate fiber, 3 parts of polyacrylamide, 1 part of silicon carbide whisker, 3 parts of corundum powder, 2 parts of alumina, and 1 part of yttrium oxide.
[0051] In the light refractory layer 2 of the composite heat-insulating brick for the rotary kiln lining, the weight parts of each raw material are 7 parts of cenospheres, 8 parts of alumina hollow balls, 5 parts of zirconia hollow balls, 9 parts of expanded perlite, 7 parts of dolomite powder, 12 parts of kaolin, 2 parts of carbon fiber, 4 parts of mullite powder, 2 parts of zirconia, and 1 part of cerium oxide.
[0052] The preparation method of the above-mentioned composite heat-insulating brick for the rotary kiln lining includes the following steps:
[0053] S1. Raw material mixing:
[0054] Preparation of the heat-insulating base layer 3 powder: Weigh each component raw material according to the formula, then put the raw materials into a mixer and mix them. Control the rotation speed of the mixer at 80 - 100 r / min and the mixing time at 20 - 30 min. After mixing, obtain the heat-insulating base layer 3 powder;
[0055] Preparation of the light refractory layer 2 powder: Weigh each component raw material according to the formula, then put the raw materials into a mixer and mix them. Control the rotation speed of the mixer at 60 - 80 r / min and the mixing time at 40 - 60 min to obtain the light refractory layer powder;
[0056] S2. Pressing the brick blank: Adopt the isostatic pressing method. First, pour the heat-insulating base layer 3 powder into the heat-insulating base layer cavity in the mold, apply a pre-pressure of 1 - 1.5 MPa, and maintain it for 2 - 3 min; then pour the light refractory layer 2 powder into the light refractory cavity in the mold, also apply a pre-pressure of 1 - 1.5 MPa, and maintain it for 2 - 3 min. Then remove the middle partition board and press it through an isostatic press. Control the pressing pressure at 2.4 - 2.6 MPa, the number of pressing times at 3 - 5 times, and the holding time for each time at 1 - 2 min. After pressing, obtain a composite heat-insulating brick blank with a gradient structure, so that the thermal expansion coefficient of the brick body gradually changes from the heat-insulating base layer 3 to the light refractory layer 2;
[0057] S3. Sintering:
[0058] Sintering of the brick blank: Put the composite heat-insulating brick blank into a sintering furnace, heat it up to 1300 - 1600 °C at a heating rate of 5 - 10 °C / min, keep it warm for 8 - 12 h, and then cool it to room temperature at a cooling rate of 3 - 5 °C / min to form a composite heat-insulating brick;
[0059] Example 2:
[0060] The difference between this example and the above Example 1 is:
[0061] In the heat-insulating base layer 3 of the composite heat-insulating brick for the rotary kiln lining, there are 2 parts of polyacrylamide and 0.75 parts of silicon carbide whiskers.
[0062] In the lightweight refractory layer 2 of the composite heat-insulating brick for the rotary kiln lining, there are 1.5 parts of carbon fiber and 0.75 parts of cerium oxide.
[0063] Example 3:
[0064] The differences between this example and the above Examples 1 and 2 are as follows:
[0065] In the heat-insulating base layer 3 of the composite heat-insulating brick for the rotary kiln lining, there is 1 part of polyacrylamide and 0.5 parts of silicon carbide whiskers.
[0066] In the lightweight refractory layer 2 of the composite heat-insulating brick for the rotary kiln lining, there is 1 part of carbon fiber and 0.5 parts of cerium oxide.
[0067] Table 1:
[0068] Comparison Example 1 Example 2 Example 3 Standard value Elastic modulus (GPa) 35 30 25 20 Hardness (Mohs hardness) 7.5 6 5.5 5 Porosity (%) 28 30 35 40
[0069] The comparisons in Table 1 above are the elastic modulus, hardness, and porosity of the composite heat-insulating brick. The standard values in Table 1 above are obtained from the case where no polyacrylamide and silicon carbide whiskers are added to the heat-insulating base layer 3, and no carbon fiber and cerium oxide are added to the lightweight refractory layer 2. By changing the raw material components in each example, the results of Examples 1 - 3 in Table 1 are obtained through experiments. It can be seen from Table 1 that by adding polyacrylamide and silicon carbide whiskers to the heat-insulating base layer 3, and adding carbon fiber and cerium oxide to the lightweight refractory layer 2 at the same time, the elastic modulus, hardness, and porosity of the composite heat-insulating brick can be optimized, thereby reducing the cracks generated in the composite heat-insulating brick, and further improving the problem that the heat-insulating brick used for the traditional rotary kiln lining may generate cracks under the action of thermal shock during the operation of the rotary kiln due to frequent temperature fluctuations, resulting in a decline in the performance and service life of the heat-insulating brick.
[0070] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A composite heat-insulating brick for a rotary kiln lining, comprising a connecting column (1), a lightweight refractory layer (2) and a heat-insulating base layer (3), characterized in that: The heat-insulating base layer (3) comprises the following raw materials in parts by weight: 10-15 parts of silica fine powder, 4-7 parts of aluminum silicate, 3-5 parts of aluminum silicate fiber, 1-3 parts of polyacrylamide, 0.5-1 parts of silicon carbide whisker, 2-3 parts of corundum powder and 1.5-3 parts of additives; the lightweight refractory layer (2) comprises the following raw materials in parts by weight: 4-7 parts of floating beads, 5-8 parts of hollow alumina balls, 2-5 parts of hollow zirconia balls, 5-9 parts of expanded perlite, 3-7 parts of dolomite powder, 7-12 parts of kaolin, 1-2 parts of carbon fiber, 3-4 parts of mullite powder and 1.5-3 parts of additives. The connecting column (1) comprises the following raw materials in parts by weight: 2-5 parts of composite fiber, 1-3 parts of expanded vermiculite, 2-7 parts of aluminum oxide powder, 3-5 parts of magnesium oxide, 0.5-1 parts of yttrium oxide, 0.5-1 parts of silicon carbide whiskers and 1-2 parts of corundum particles.
2. The composite heat-insulating brick for rotary kiln lining according to claim 1, characterized in that: The additives of the heat-insulating base layer (3) include the following raw materials in parts by weight: 1-2 parts of aluminum oxide and 0.5-1 parts of yttrium oxide, and the additives of the lightweight refractory layer (2) include the following raw materials in parts by weight: 1-2 parts of zirconium oxide and 0.5-1 parts of cerium oxide.
3. The composite heat-insulating brick for rotary kiln lining according to claim 1, characterized in that: The particle sizes of the components in the thermal insulation base layer (3) are respectively 40-80 μm silica fine powder, 80-120 μm aluminum silicate, 20-30 μm polyacrylamide, 60-80 μm aluminum oxide, 20-30 μm yttrium oxide, and 80-100 μm corundum powder. The length of the aluminum silicate fiber in the thermal insulation base layer (3) is 1-2 cm.
4. The composite heat-insulating brick for rotary kiln lining according to claim 1, characterized in that: The particle sizes of the components in the lightweight refractory layer (2) are respectively 1-2 mm floating beads, 0.5-1 mm hollow alumina balls, 1-1.5 mm hollow zirconia balls, 1-2 mm expanded perlite, 20-40 μm dolomite powder, 60-100 μm kaolin, 80-100 μm zirconium oxide, 20-30 μm cerium oxide, and 80-120 μm mullite powder. The length of the carbon fiber in the lightweight refractory layer (2) is 5-10 mm.
5. The composite heat-insulating brick for rotary kiln lining according to claim 4, characterized in that: The length of each component in the connecting column (1) is 2-3 cm for alumina fiber, 1-3 cm for carbon fiber, 0.5-2 cm for graphite fiber, and 10-20 μm for silicon carbide whisker. The particle size of each component in the connecting column (1) is 0.5-1.5 mm for expanded vermiculite, 60-80 μm for alumina powder, 20-60 μm for magnesium oxide, 20-30 μm for yttrium oxide, and 1-2 mm for corundum particles.
6. The composite heat-insulating brick for rotary kiln lining according to claim 1, characterized in that: A lightweight fire-resistant layer (2) is arranged on the upper part of the heat-insulating base layer (3), a connecting column (1) is arranged inside the lightweight fire-resistant layer (2), a mounting groove (4) is opened on the upper surface of the lightweight fire-resistant layer (2), and the lightweight fire-resistant layer (2) is located inside the mounting groove (4).
7. The composite heat-insulating brick for rotary kiln lining according to claim 6, characterized in that: The connecting column (1) is in an N-shape.
8. A method for preparing composite heat-insulating bricks for rotary kiln lining, characterized in that The following steps are involved: S1. Raw material mixing: Preparation of thermal insulation base layer (3) powder: weigh the raw materials of each component according to the formula, and then put the raw materials into a mixer for mixing. The speed of the mixer is controlled to be 80-100 r / min, and the mixing time is 20-30 min. After the mixing is completed, the thermal insulation base layer (3) powder is obtained; Lightweight refractory layer (2) powder preparation: weigh the raw materials of each component according to the formula, then put the raw materials into a mixer for mixing, control the mixer speed to 60-80r / min, and the mixing time to 40-60min to obtain a lightweight refractory layer powder; (1) Preparation of powder for connecting column: weigh the raw materials of each component according to the formula, and then put the raw materials into a mixer for mixing, control the mixer speed to 100-120r / min, and mix for 5-10min to obtain powder for connecting column; S2. Pressing the brick blank: using an isostatic pressing method, first pour the powder of the heat insulating base layer (3) into the heat insulating base layer cavity in the mold, apply a pre-pressure of 1-1.5MPa, and keep it for 2-3min; then pour the powder of the lightweight refractory layer (2) into the lightweight refractory cavity in the mold, also apply a pre-pressure of 1-1.5MPa, and keep it for 2-3min, then take out the middle partition, and press it with an isostatic press. The pressing pressure is controlled at 2.4-2.6MPa, the pressing number is 3-5 times, and the holding time of each time is 1-2min. After the pressing is completed, a composite heat insulating brick blank with a gradient structure is obtained, so that the thermal expansion coefficient of the brick body gradually changes from the heat insulating base layer (3) to the lightweight refractory layer (2); S3, preparing a connecting column: putting the powder of the connecting column (1) into a rubber sleeve, repeatedly compacting it 5-8 times, and then putting it into a cold isostatic press for pressing. The working pressure of the cold isostatic press is controlled at 8.5-9.3 MPa, and the pressing time is 20-30 min. After the pressing is completed, the rubber sleeve is removed to obtain a connecting column blank; S4, sintering: Brick sintering: Put the composite thermal insulation brick into the sintering furnace, raise the temperature to 1300-1600℃ at a rate of 5-10℃ / min, keep it warm for 8-12h, and then cool it to room temperature at a rate of 3-5℃ / min to form a composite thermal insulation brick; Sintering of the connecting column blank: Place the connecting column blank in another sintering furnace, raise the temperature to 1500-1700°C at a heating rate of 8-12°C / min, keep it warm for 5-8h, and then cool it to room temperature at a cooling rate of 4-6°C / min.