A diatomite porous ceramic thermal insulation material based on foaming method and preparation method thereof

Abstract

The present invention discloses a diatomite porous ceramic thermal insulation material based on a foaming method and a preparation method thereof, wherein the method comprises the steps of placing diatomite in a furnace for calcination, cooling the furnace to room temperature after completion, and then soaking, filtering, and washing the diatomite with concentrated sulfuric acid to obtain modified diatomite; uniformly mixing the modified diatomite with aluminate cement and starch according to a certain mass ratio to obtain a mixture; sequentially adding ionized water, a surfactant, a foam stabilizer, a thickener, and a high-silica fiber into a container according to a certain mass ratio, stirring evenly, and obtaining a mixed solution; pouring the obtained mixture into the mixed solution and stirring evenly, then adding a foaming agent, and stirring evenly to obtain a slurry; pouring the slurry into a mold and letting it stand, and then placing it in a furnace for calcination, and obtaining a diatomite porous ceramic thermal insulation material after cooling the furnace to room temperature after completion. The diatomite thermal insulation material prepared by the present invention has the advantages of light weight, low bulk density, high mechanical strength, and good thermal insulation performance.

Description

Technical Field

[0001] The invention relates to a diatomaceous earth porous ceramic heat insulating material based on a foaming method and a preparation method thereof. Background Art

[0002] Diatomaceous earth is a porous, lightweight siliceous sedimentary rock, mainly composed of the accumulation of diatom fossils. It has the characteristics of environmental protection, low density, large surface area, excellent thermal insulation performance, good filtration and sound insulation. It is often used in thermal insulation, fire prevention, filtration, moisture absorption and humidity control.

[0003] With the development of industrialization and the implementation of energy conservation and emission reduction, higher requirements are placed on the thermal insulation performance of the thermal insulation layer of the industrial kiln lining. The thermal insulation performance depends on the pore structure and thermal conductivity of the material itself. Since diatomaceous earth has a very low thermal conductivity, it has good thermal insulation performance and can be used for the thermal insulation layer of the industrial kiln lining to help maintain the high temperature in the furnace, reduce energy loss and improve production efficiency. However, traditional diatomaceous earth thermal insulation materials have problems such as long production cycle, high volume density and poor mechanical properties. For example, a diatomaceous earth thermal insulation material disclosed in Chinese patent document CN202350518 Insulation bricks, with diatomaceous earth and sawdust as the main raw materials, adopt a pressing process to make diatomaceous earth insulation bricks. This patent has the disadvantages of high production energy consumption, large production process area, limited drying environment, long drying cycle, and the resulting product volume density is as high as 0.68g / cm3; another Chinese patent document CN116143504A discloses a new diatomaceous earth insulation brick production method, with diatomaceous earth, perlite and trace elements as the main raw materials, adopts a pressing process to make diatomaceous earth insulation bricks. This patent has the disadvantages of long production cycle, limited drying environment, and high volume density of the resulting product. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention provides a diatomite porous ceramic thermal insulation material based on a foaming method and a preparation method thereof, the purpose of which is to provide a preparation method of a diatomite porous ceramic thermal insulation material based on a foaming method that is energy-saving, lightweight, has a low bulk density, excellent mechanical properties, good thermal insulation performance and a short production cycle. The diatomite porous ceramic thermal insulation material based on a foaming method prepared by this method has the advantages of low energy consumption, lightweight, low bulk density, high mechanical strength, good thermal insulation performance and the like. The specific technical scheme is as follows: The present invention provides a preparation method of the aforementioned diatomite porous ceramic thermal insulation material based on a foaming method, comprising the following steps:

[0005] S1, calcining diatomite in a furnace, cooling it to room temperature with the furnace, and then soaking, filtering and washing it with concentrated sulfuric acid to obtain modified diatomite;

[0006] S2, uniformly mixing the modified diatomite obtained in step S1 with aluminate cement and starch in a certain mass ratio to obtain a mixture for later use;

[0007] S3, adding ionized water, surfactant, foam stabilizer, thickener and high silica fiber into the container in a certain mass ratio, stirring evenly to obtain a mixed solution for standby use;

[0008] S4, pouring the mixture obtained in step S2 into the mixed solution of step S3 and stirring evenly, then adding a foaming agent, stirring twice, and stirring evenly to obtain a slurry;

[0009] S5, pouring the slurry into a mold and letting it stand, then putting it into a furnace for calcination, and after completion, cooling it to room temperature in the furnace to obtain a diatomaceous earth porous ceramic thermal insulation material.

[0010] As a preferred technical solution, the calcination parameters in step S1 are set as: temperature 200-500° C., time 0.5-2 h.

[0011] As a preferred technical solution, the concentrated sulfuric acid soaking, filtering and washing in step S1 are specifically performed as follows: the cooled diatomaceous earth and concentrated sulfuric acid with a concentration of 98% are sequentially added into a container in a mass ratio of 1:1 to 3:1, stirred evenly, and allowed to stand at room temperature for 1 to 3 hours, and then sodium hydroxide is added for neutralization, and the diatomaceous earth is washed with deionized water until the pH value is close to neutral, and the modified diatomaceous earth is obtained after drying.

[0012] As a preferred technical solution, the contents of the components in the mixture in step S2 are as follows: 50-70% of the modified diatomaceous earth, 10-20% of aluminate cement, and 20-30% of starch.

[0013] As a preferred technical solution, the mass ratios of deionized water, surfactant, foam stabilizer, thickener and high-silica fiber contained in the mixed solution in step S3 are 1: (0.002-0.004): (0.001-0.002): (0.002-0.004): (0.003-0.012) respectively.

[0014] As a preferred technical solution, the stirring speed in step S4 is 1000-1200 rpm, and the time is 1-2 min; the secondary stirring speed is 1000-1200 rpm, and the time is 2-4 min;

[0015] The volume percentage of the foaming agent is 0.2-0.5%.

[0016] As a preferred technical solution, the standing time in step S5 is 0.5 to 1 day;

[0017] The calcination parameters are set as: heating rate 2-5°C / min, temperature 800-1100°C, and time 1-4h.

[0018] As a preferred technical solution, the SiO2 content in the modified diatomaceous earth in step S1 is ≥85wt% and the particle size is ≤74μm;

[0019] The Al2O3 content in the aluminate cement in step S2 is ≥67wt% and the particle size is ≤74μm;

[0020] In step S3, the foam stabilizer is sodium carboxyethyl cellulose; the surfactant is one of fatty alcohol polyoxyethylene ether or polyisobutylene maleic anhydride copolymer; the thickener is calcium lignin sulfonate;

[0021] The foaming agent in step S4 is one of trimethyl lauryl sodium sulfate or polyethylene glycol.

[0022] The beneficial effects of the present invention are:

[0023] (1) The specific implementation method of the diatomite porous ceramic insulation material of the present invention is to first mix the modified diatomite, aluminate cement and starch evenly into a mixture, then mix it evenly with the mixed solution, and finally mix it with a foaming agent, stir it, and then burn it in an air atmosphere after drying. This method has a simple manufacturing process and a low production cost.

[0024] (2) The diatomaceous earth porous ceramic thermal insulation material of the present invention uses diatomaceous earth, aluminate cement and starch as raw materials and adopts a foaming method, which not only increases the flexibility of product molding, but also improves production efficiency and saves energy; during the production process, the high-temperature carbonization effect of starch increases the porosity of the product, thereby reducing the volume density of the product, making the product light and having excellent thermal insulation performance; during the production process, the hydration effect of cement accelerates the drying rate of the product, solves the problems of long drying time and limited drying conditions, and shortens the production cycle; because the high-silica fibers cross each other to form a network structure, the expansion of cracks is hindered, stress concentration is reduced, and the mechanical properties of the material are improved.

[0025] (3) The raw material modified diatomaceous earth in the diatomaceous earth porous ceramic insulation material of the present invention has the following advantages: (1) The production process removes organic residues in the diatomaceous earth, making its pore structure clearer and more open, thereby improving its chemical stability and physical properties; (2) The size and distribution of diatomaceous earth particles are adjusted, thereby adjusting its fluidity during the foaming process; (3) The moisture in the diatomaceous earth is eliminated, improving its high-temperature performance; (4) The adsorption force between diatomaceous earth particles is reduced, thereby improving its dispersibility.

[0026] (4) The diatomite porous ceramic thermal insulation material prepared by the present invention has been tested: the apparent porosity is 78-90%; the volume density is 0.41-0.52 g / cm3; the flexural strength at room temperature is 0.8-1.5 MPa, and the compressive strength is 1.1-1.8 MPa; the thermal conductivity coefficients at 25°C, 200°C, 400°C, 600°C and 800°C are 0.105-0.132 W / (m·K), 0.058-0.076 W / (m·K), 0.062-0.086 W / (m·K), 0.088-0.103 W / (m·K) and 0.097-0.126 W / (m·K), respectively. It can be seen from the above data that the diatomite porous ceramic thermal insulation material prepared by the present invention has the advantages of light weight, high flexural strength at room temperature, high compressive strength, good thermal insulation performance, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an XRD diagram of a diatomite porous ceramic thermal insulation material prepared by the present invention;

[0028] Figure 2 yes Figure 1 The SEM image of the pores inside the porous diatomaceous earth ceramic insulation material is shown. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with embodiments.

[0030] Example 1

[0031] S1. Put diatomaceous earth into a furnace and calcine it at 200-500° C. for 0.5-2 hours, then cool it to room temperature with the furnace, then add the cooled diatomaceous earth and 98% concentrated sulfuric acid in a mass ratio of 1:1-3:1 into a container, stir evenly, let it stand at room temperature for 1-3 hours, then add sodium hydroxide to neutralize it, wash the diatomaceous earth with deionized water until the pH value is close to neutral, and obtain modified diatomaceous earth after drying.

[0032] S2: adding the modified diatomite obtained in step S1, aluminate cement and starch into a container in order according to the mass percentage of 50-65wt% of the modified diatomite, 15-20wt% of the aluminate cement and 20-30wt% of the starch, mixing evenly to obtain a mixture for standby use;

[0033] S3: Add deionized water, surfactant, foam stabilizer, thickener and high silica fiber into a container in the mass ratio of 1: (0.002-0.004): (0.001-0.002): (0.002-0.004): (0.003-0.012), stir evenly to obtain a mixed solution for standby use;

[0034] S4: pouring the mixture obtained in step S2 into the mixed solution of step S3, stirring at 1000-1200 rpm for 1-2 min, then adding 0.2-0.5 vol.% foaming agent and stirring again at 1000-1200 rpm for 2-4 min to obtain a slurry;

[0035] S5: pouring the slurry into a mold and letting it stand for 0.5 to 1 day, then placing it in a furnace, heating the furnace to 800 to 950° C. at a rate of 4 to 5° C. / min, keeping the temperature for 3 to 4 hours, and then cooling it to room temperature with the furnace to obtain a diatomite porous ceramic thermal insulation material;

[0036] Wherein, the surfactant in step S3 is fatty alcohol polyoxyethylene ether; and the foaming agent in step S4 is polyethylene glycol.

[0037] Example 2

[0038] Compared with Example 1, the only difference between this embodiment and Example 1 is that the surfactant in step S3 is polyisobutylene maleic anhydride copolymer; the foaming agent in step S4 is sodium trimethyl lauryl sulfate; and the other steps and raw materials are the same.

[0039] Example 3

[0040] Compared with Example 1, the only difference between this example and Example 1 is that the surfactant in step S3 is fatty alcohol polyoxyethylene ether; the foaming agent in step S4 is sodium trimethyl lauryl sulfate; and the other steps and raw materials are the same.

[0041] Example 4

[0042] Compared with Example 1, the only difference between this example and Example 1 is that the surfactant in step S3 is polyisobutylene maleic anhydride copolymer; the foaming agent in step S4 is polyethylene glycol; and the other steps and raw materials are the same.

[0043] The components and contents of the preparation method of diatomite porous ceramic thermal insulation material based on the foaming method in each embodiment are shown in Table 1.

[0044] The test data of the diatomaceous earth porous ceramic thermal insulation material based on the foaming method in each embodiment are shown in Table 2.

[0045] Table 1

[0046]

[0047] Table 2

[0048]

[0049] The test data of the diatomite porous ceramic thermal insulation material prepared by the present invention can be seen from Table 2: the apparent porosity is 78-90%; the volume density is 0.41-0.52 g / cm 3 The room temperature flexural strength is 0.8-1.5 MPa, and the compressive strength is 1.1-1.8 MPa; the thermal conductivity coefficients at 25°C, 200°C, 400°C, 600°C and 800°C are 0.105-0.132 W / (m·K), 0.058-0.076 W / (m·K), 0.062-0.086 W / (m·K), 0.088-0.103 W / (m·K) and 0.097-0.126 W / (m·K), respectively. It can be seen from the above data that the diatomaceous earth porous ceramic thermal insulation material prepared by the present invention has the advantages of light weight, high room temperature flexural strength, high compressive strength, good thermal insulation performance, etc.

[0050] from Figure 1 It can be seen that the main phase of the diatomite porous ceramic thermal insulation material prepared in the present invention is SiO2.

[0051] from Figure 2 It can be seen that the diatomite porous ceramic thermal insulation material prepared in the present invention has a porous structure, high porosity, and uniform pore distribution, which reduces the volume density of the diatomite porous ceramic thermal insulation material and improves the thermal insulation performance of the diatomite porous ceramic thermal insulation material.

[0052] In general, the specific implementation method of the diatomite porous ceramic thermal insulation material of the present invention is to first mix the modified diatomite, aluminate cement and starch evenly into a mixture, then mix evenly with the mixed solution, and finally mix and stir with the foaming agent, dry and then fire in an air atmosphere. The method has a simple manufacturing process and low production cost. The diatomite porous ceramic thermal insulation material of the present invention uses diatomite, aluminate cement and starch as raw materials, and adopts a foaming method, which not only increases the flexibility of product molding, but also improves production efficiency and saves energy; during the production process, due to the high-temperature carbonization of starch, the porosity of the product is increased, thereby reducing the volume density of the product, so that the product has the advantages of light weight and excellent thermal insulation performance; during the production process, due to the hydration of cement, the drying rate of the product is accelerated, the problems of long drying time and limited drying conditions of the product are solved, and the production cycle is shortened; because the high-silica fibers cross each other to form a network structure, the expansion of cracks is hindered, stress concentration is reduced, and the mechanical properties of the material are improved. The raw material modified diatomaceous earth in the diatomaceous earth porous ceramic insulation material of the present invention has the following advantages: the production process removes organic residues in the diatomaceous earth, making its pore structure clearer and more open, improving its chemical stability and physical properties; adjusting the size and distribution of diatomaceous earth particles, and then adjusting its fluidity during the foaming process; eliminating moisture in the diatomaceous earth, improving its high-temperature performance; reducing the adsorption force between diatomaceous earth particles, and improving its dispersibility. The diatomite porous ceramic thermal insulation material prepared by the present invention is tested: the apparent porosity is 78-90%; the volume density is 0.41-0.52 g / cm3; the flexural strength at room temperature is 0.8-1.5 MPa, and the compressive strength is 1.1-1.8 MPa; the thermal conductivity coefficients at 25°C, 200°C, 400°C, 600°C and 800°C are 0.105-0.132 W / (m·K), 0.058-0.076 W / (m·K), 0.062-0.086 W / (m·K), 0.088-0.103 W / (m·K) and 0.097-0.126 W / (m·K), respectively. It can be seen from the above data that the diatomite porous ceramic thermal insulation material prepared by the present invention has the advantages of light weight, high flexural strength at room temperature, high compressive strength, good thermal insulation performance, etc., and has good application value.

[0053] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view. In addition, it should be understood that although this specification is described in accordance with the implementation mode, it does not include only one technical solution. This narrative mode of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method, characterized in that: The steps include: S1, calcining diatomite in a furnace, cooling it to room temperature with the furnace, and then soaking, filtering and washing it with concentrated sulfuric acid to obtain modified diatomite; S2, uniformly mixing the modified diatomite obtained in step S1 with aluminate cement and starch according to a certain mass percentage to obtain a mixture for later use; S3, adding deionized water, surfactant, foam stabilizer, thickener, and high silica fiber into the container in a certain mass ratio, stirring evenly to obtain a mixed solution for standby use; S4, pouring the mixture obtained in step S2 into the mixed solution in step S3 and stirring evenly, then adding a foaming agent, and stirring evenly again to obtain a slurry; S5, pouring the slurry obtained in step S4 into a mold and letting it stand, and then putting it into a furnace for calcination. After completion, the diatomaceous earth porous ceramic thermal insulation material can be obtained after cooling to room temperature in the furnace.

2. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The calcination parameters in step S1 are set as: temperature 200-500° C., time 0.5-2 h.

3. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The concentrated sulfuric acid soaking, filtering and washing in step S1 are specifically performed as follows: the cooled diatomaceous earth and concentrated sulfuric acid with a concentration of 98% are sequentially added into a container in a mass ratio of 1:1 to 3:1, stirred evenly, and allowed to stand at room temperature for 1 to 3 hours, and then sodium hydroxide is added for neutralization, and then the diatomaceous earth is washed with deionized water until the pH value is close to neutral, and the modified diatomaceous earth is obtained after drying.

4. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The contents of each component of the mixture in step S2 in terms of mass percentage are: 50-70% modified diatomaceous earth, 10-20% aluminate cement, and 20-30% starch.

5. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The mass ratios of deionized water, surfactant, foam stabilizer, thickener and high-silica fiber contained in the mixed solution in step S3 are 1: 0.002~0.004: 0.001~0.002: 0.002~0.004: 0.003~0.012 respectively.

6. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The stirring speed in step S4 is 1000-1200 rpm, and the time is 1-2 min; the stirring speed again is 1000-1200 rpm, and the time is 2-4 min; The volume percentage of the foaming agent is 0.2-0.5%.

7. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The standing time in step S5 is 0.5 to 1 day; The calcination parameters are set as: heating rate 2-5°C / min, temperature 800-1100°C, and time 1-4h.

8. The method for preparing a diatomite porous ceramic thermal insulation material based on a foaming method according to claim 1, characterized in that: The modified diatomaceous earth in step S1 has a SiO2 content of ≥85wt% and a particle size of ≤74μm; The Al2O3 content in the aluminate cement in step S2 is ≥67wt% and the particle size is ≤74μm; In step S3, the foam stabilizer is sodium carboxyethyl cellulose; the surfactant is one of fatty alcohol polyoxyethylene ether or polyisobutylene maleic anhydride copolymer; the thickener is calcium lignin sulfonate; The foaming agent in step S4 is one of trimethyl lauryl sodium sulfate or polyethylene glycol.

9. A diatomite porous ceramic thermal insulation material based on a foaming method, characterized in that: The diatomaceous earth porous ceramic thermal insulation material based on the foaming method is a diatomaceous earth porous ceramic thermal insulation material based on the foaming method prepared according to the preparation method of the diatomaceous earth porous ceramic thermal insulation material based on any one of claims 1 to 9.

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