Micro-expansion high-temperature resistant insulation board and preparation method thereof

Abstract

The invention discloses a micro-expansion high-temperature resistant insulation board and a preparation method thereof. The raw materials comprise, by mass percentage, 30% to 75% of low-temperature expanded vermiculite, 5% to 30% of kyanite and / or andalusite, 5% to 20% of premixed powder, and 15% to 40% of a binder. The low-temperature expanded vermiculite is incompletely expanded vermiculite obtained by expanding raw vermiculite at 400 to 600° C. for 1 to 2 minutes. Based on 100% of the total mass of the raw materials, the premixed powder comprises 1% to 5% of explosion-proof fiber micropowder, 1% to 3% of a dispersant, 1% to 10% of light-burned magnesia micropowder, 1% to 5% of silicon micropowder, and 1% to 5% of an admixture. The admixture is at least one of sodium tripolyphosphate, aluminum hexametaphosphate, sodium fluorosilicate, and potassium fluorosilicate. The binder is a modified sodium silicate and / or potassium silicate solution to which aluminum oxide and / or zirconium oxide fibers are added. Preparation method: the raw materials are mixed and then molded, and dried at 120-300°C for 2-4 hours to obtain a slightly expanded high-temperature resistant insulation board.

Description

Technical Field

[0001] The present invention relates to the field of heat-insulating refractory materials, and in particular to a micro-expansion high-temperature resistant heat-insulating board and a preparation method thereof. Background Art

[0002] Insulating refractory materials are increasingly being used as insulation layers for thermal equipment. Currently, the industries where these materials are widely used include metallurgy, nonferrous metals, chemicals, and petroleum. Iron and steel metallurgy and nonferrous metals are the most widely used, accounting for approximately 70%.

[0003] There are many types of insulating refractory materials in use on the market, including asbestos fiber products, lightweight clay bricks, porous mullite bricks, calcium silicate boards, and vermiculite boards. Each of these insulating refractory materials has its own drawbacks. Asbestos products lack strength and refractoriness and contain hazardous substances. Lightweight clay bricks and mullite bricks have insufficient thermal conductivity and inadequate insulation performance. While calcium silicate boards offer excellent insulation in the early stages of use, their operating temperature and strength are low. They are prone to compression and pulverization in later life, significantly reducing their insulation effectiveness.

[0004] Vermiculite board is currently an ideal thermal insulation refractory material. Patent publication number CN 115893984A discloses a ceramic vermiculite insulation board that can be used as the insulation layer of aluminum electrolytic cells. The board is composed of the following raw materials by weight: 55-65% vermiculite mixture, 4-25% spherical silica powder, 8-45% siliceous clay, 3-6% sodium bentonite, 1-4% lepidolite powder, 0.5-3% boric acid powder, 1-9% calcium lignin sulfonate, and 0.01-0.05% dispersant. The patent specification with publication number CN105777156 A discloses a lightweight, fire-resistant and thermal-insulating vermiculite board with an inorganic glue as an adhesive. First, phosphoric acid, aluminum hydroxide, aluminum powder, aluminum silicate and water are mixed evenly in a certain proportion, and the inorganic glue is prepared under heating conditions. Then, the inorganic glue is added with bentonite, diluted with water, and then mixed with expanded vermiculite in a certain proportion. The mixture is stirred evenly, and the mixture is placed in a mold. After pre-pressing, hot pressing, demolding and trimming, a lightweight thermal-insulating board is obtained.

[0005] However, vermiculite board also has its disadvantages. Since it uses vermiculite that is fully expanded at a conventional temperature of 850-1100°C, this vermiculite has a high impurity content and will produce large sintering shrinkage above 900°C, which means that its operating temperature is not high enough. The maximum continuous use temperature is about 1100°C, and the shrinkage rate at this temperature is large, reaching more than 4%, which can easily lead to safety risks in use.

[0006] In addition, in the preparation process of thermal insulating refractory materials, the baking process is the part with the largest energy consumption ratio. Generally, the baking time of products is more than 10 hours. Therefore, if the baking time can be shortened, energy saving and consumption reduction will be very meaningful. Summary of the Invention

[0007] In response to the above-mentioned technical problems and the shortcomings in the field, the present invention provides a micro-expansion high-temperature resistant insulation board, which has the characteristics of good high-temperature volume stability, no shrinkage, high temperature durability, high strength and good thermal insulation. It has a fast production speed, high efficiency and low energy consumption. It can be used as an insulation layer or even a permanent layer for high-temperature thermal equipment such as mixing cars, ladles, steel ladles, converters, RH and tundishes.

[0008] A micro-expansion high-temperature resistant insulation board, the raw materials of which are composed, by mass percentage, of:

[0009]

[0010] The low-temperature expanded vermiculite is an incompletely expanded vermiculite obtained by expanding the raw vermiculite at 400-600°C for 1-2 minutes;

[0011] Taking the total mass of the raw materials as 100%, the composition of the premixed powder includes:

[0012]

[0013] The admixture is at least one of sodium tripolyphosphate, aluminum hexametaphosphate, sodium fluorosilicate, and potassium fluorosilicate;

[0014] The binder is a modified sodium silicate and / or potassium silicate solution added with alumina and / or zirconia fibers.

[0015] If raw vermiculite is directly used as the raw material, the product will expand too much during application, which is not conducive to practical application.

[0016] The present invention adopts incompletely expanded vermiculite, which can make the product have a certain continuous micro-expansion in the low temperature stage below 900°C during use, while the introduced kyanite and / or andalusite can ensure that the product maintains a certain micro-expansion in the medium and high temperature stage above 900°C.

[0017] In one embodiment, in the micro-expanded high-temperature resistant insulation board, the particle size of the low-temperature expanded vermiculite may be no greater than 1 mm.

[0018] In one embodiment, in the micro-expansion high temperature resistant insulation board, the particle size of the kyanite and / or andalusite may be no greater than 1 mm.

[0019] The present invention adopts explosion-proof fiber powder, that is, the explosion-proof fiber length is micron-level. On the one hand, it eliminates the shortcomings of ordinary millimeter or centimeter-level fibers that are easy to clump and agglomerate. On the other hand, it can be quickly decomposed during the baking process to produce micron-level pore channels, ensuring that the product can achieve the purpose of fast baking and improved thermal insulation. The added dispersant can be an alkyl tertiary amine phosphate specially used for fiber, which has a very good dispersing effect. The added light-burned magnesium powder and silicon powder can form a magnesium-silicon-water binding effect, thereby improving the strength of the product. The introduced admixture can play a role in dispersing and promoting solidification, ensuring that the product has good semi-finished product and finished product strength. The use of premixed powder can ensure that it can be fully and evenly mixed with other main raw materials.

[0020] The present invention adopts premixed powder. Since the components in the premixed powder are all fine powders, it is not easy to mix evenly. Therefore, it is necessary to premix first, and then add the fine powders into the aggregate for further mixing after the fine powders are mixed evenly.

[0021] In one embodiment, the method for preparing the premixed powder includes: uniformly mixing explosion-proof fiber powder, dispersant, light-burned magnesium powder, silicon powder, and additives by ball milling to obtain the premixed powder. Furthermore, the ball milling time may be 10 to 20 minutes.

[0022] The binder of the present invention is a modified potassium silicate and / or sodium silicate solution, which can be more evenly dispersed in the material, more fully react with the mixed powder to form an interwoven structure, and further improve the strength of the product.

[0023] Based on the total mass of the raw materials being 100%, the amount of the alumina and / or zirconia fibers in the binder may account for 1% to 3%.

[0024] In one embodiment, in the micro-expansion high-temperature resistant insulation board, the diameter of the alumina and / or zirconia fibers may be in the micron order.

[0025] In one embodiment, the binder preparation method includes adding alumina and / or zirconia fibers having a diameter in the micrometer range to a sodium silicate and / or potassium silicate solution having a modulus of 2 to 4, and stirring at 40 to 80°C to obtain the binder. Stirring at 40 to 80°C ensures a low solution viscosity, making it easier to disperse the alumina and / or zirconia fibers. If the temperature is too low, the solution viscosity will be high, making it difficult to disperse the alumina and / or zirconia fibers.

[0026] The present invention also provides a method for preparing the micro-expansion high-temperature resistant insulation board, comprising mixing low-temperature expanded vermiculite, kyanite and / or andalusite, premixed powder and a binder, performing compression molding, and drying at 120-300° C. for 2-4 hours to obtain the micro-expansion high-temperature resistant insulation board.

[0027] In one embodiment, in the method for preparing the micro-expansion high-temperature resistant insulation board, the molding pressure may be 3 to 50 MPa.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The low-temperature expanded vermiculite introduced in the present invention is an incompletely expanded vermiculite. When used together with kyanite and / or andalusite, it can ensure that the product has continuous micro-expansion in both low-temperature and medium-high-temperature stages during use, and will not produce excessive shrinkage that affects the structure of the masonry and thus creates safety risks.

[0030] The present invention adopts a dual inorganic salt combination system of magnesium silicate water and potassium silicate and / or sodium silicate, so that the product has high strength.

[0031] The introduction of micron explosion-proof fibers can greatly increase the baking speed of the product, save energy and reduce consumption. At the same time, the micron pore channels formed can further improve the thermal insulation performance of the product.

[0032] The use of fiber-modified binders enables the formation of a fully interwoven structure within the product, further improving the strength of the product.

[0033] Compared with ordinary vermiculite boards, the micro-expansion high-temperature resistant insulation board of the present invention has a durable temperature of up to 1300°C due to its continuous micro-expansion, and has high strength. The thermal insulation performance will become better and better with its micro-expansion and the formation of micron-level pores inside it, and there will be no decline in thermal insulation performance in the later stage. It is more suitable for use as an insulation layer or permanent layer in high-temperature thermal equipment such as mixing cars, ladles, steel ladles, converters, RH and tundishes. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0035] In the following examples, the operating methods without specifying specific conditions are generally carried out under conventional conditions or conditions recommended by the manufacturer.

[0036] Table 1 shows the raw material compositions and amounts (unit: parts by mass) of the various examples and comparative examples.

[0037] Table 1

[0038]

[0039] In Table 1:

[0040] Fully expanded vermiculite is obtained by expanding raw vermiculite at 950℃ for 2 minutes;

[0041] Low temperature expanded vermiculite is obtained by expanding raw vermiculite at 500℃ for 1 minute;

[0042] The dispersant is alkyl tertiary amine phosphate;

[0043] The premixed powders of each embodiment and comparative example were obtained by ball milling the corresponding raw materials in Table 1 for 10 minutes;

[0044] The modified sodium silicate is prepared by adding alumina fibers with a diameter of micrometers to a sodium silicate solution with a modulus of 2 to 4 and stirring at 40 to 80° C. The mass content of the alumina fibers in the modified sodium silicate is 10% (based on the total mass of the modified sodium silicate being 100%).

[0045] The modified potassium silicate is prepared by adding zirconium oxide fibers having a diameter of micrometers to a potassium silicate solution having a modulus of 2 to 4 and stirring at 40 to 80° C. The mass content of the zirconium oxide fibers in the modified potassium silicate is 10% (based on the total mass of the modified potassium silicate being 100%).

[0046] Unmodified sodium silicate is a sodium silicate solution with a modulus of 2 to 4.

[0047] The preparation method of the insulation board of each embodiment and comparative example includes: mixing all the raw materials except the premixed powder and the binder (i.e., modified sodium silicate, modified potassium silicate or unmodified sodium silicate) for 1 minute, then mixing and stirring with the premixed powder for 2 minutes, and then mixing and stirring with the binder for 5 minutes. The resulting product is compression molded at 20 MPa and dried at 200°C for 4 hours to obtain the insulation board.

[0048] Table 2 shows the comparison of the physical and chemical properties and usage-related parameters of the insulation panels of the embodiments and comparative examples.

[0049] Table 2

[0050]

[0051] From the results in Table 2 we can see that:

[0052] The micro-expansion high-temperature resistant insulation boards prepared according to Examples 1 and 2 have high strength, exhibit micro-expansion after firing at 1100°C and 1300°C, and have low thermal conductivity.

[0053] Comparative Example 1 uses fully expanded vermiculite, which has low strength, large shrinkage in the low temperature stage, and increased thermal conductivity, and has a low applicable temperature;

[0054] Comparative Example 2 does not add andalusite or kyanite, and the shrinkage rate in the high temperature stage is too large, the thermal conductivity is high, and the thermal insulation is poor, so it is only suitable for use below 900°C;

[0055] Comparative Example 3 uses a common binder, which has too low strength, and the expansion rate and thermal conductivity at each temperature stage are increased, and the maximum operating temperature is only 1100°C;

[0056] Comparative Example 4 uses 3-10 mm explosion-proof fibers. Under the short baking time process of the present invention, the purpose of complete baking cannot be achieved, the product strength is too low, and it is easy to break during use.

[0057] The micro-expansion high-temperature resistant insulation boards prepared in Example 1 and Example 2 were used in molten iron ladles and iron mixing cars. The steel shell temperature dropped by 30 to 80°C compared with the control example, and the molten iron temperature drop was reduced by 10 to 40°C. Moreover, the boards were in good condition when used offline, without shrinkage or pulverization, achieving excellent energy-saving and emission reduction effects.

[0058] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A micro-expansion high temperature resistant insulation board, characterized in that: In terms of mass percentage, the raw material composition includes: The low-temperature expanded vermiculite is an incompletely expanded vermiculite obtained by expanding the raw vermiculite at 400-600°C for 1-2 minutes; Taking the total mass of the raw materials as 100%, the composition of the premixed powder includes: The admixture is at least one of sodium tripolyphosphate, aluminum hexametaphosphate, sodium fluorosilicate, and potassium fluorosilicate; The binder is a modified sodium silicate and / or potassium silicate solution added with alumina and / or zirconia fibers.

2. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: The particle size of the low-temperature expanded vermiculite is not greater than 1 mm.

3. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: Calculated by mass percentage, the raw material composition of the micro-expansion high-temperature resistant insulation board includes 5% to 15% of kyanite and / or andalusite.

4. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: The particle size of the kyanite and / or andalusite is not greater than 1 mm.

5. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: The dispersant is alkyl tertiary amine phosphate.

6. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: The preparation method of the premixed powder comprises: uniformly mixing explosion-proof fiber fine powder, dispersant, light-burned magnesium fine powder, silicon fine powder and additives through ball milling to obtain the premixed powder.

7. The micro-expansion high temperature resistant insulation board according to claim 6, characterized in that: The ball milling mixing time is 10 to 20 minutes.

8. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: Based on the total mass of the raw materials being 100%, the amount of the alumina and / or zirconia fibers in the binder accounts for 1% to 3%.

9. The micro-expansion high temperature resistant insulation board according to claim 1, characterized in that: The preparation method of the binder comprises: adding aluminum oxide and / or zirconium oxide fibers with a diameter of micrometer level into a sodium silicate and / or potassium silicate solution with a modulus of 2 to 4, and stirring at 40 to 80° C. to obtain the binder.

10. The method for preparing the micro-expansion high temperature resistant insulation board according to any one of claims 1 to 9, characterized in that: The low-temperature expanded vermiculite, kyanite and / or andalusite, premixed powder and a binder are mixed uniformly, molded, and dried at 120-300° C. for 2-4 hours to obtain the micro-expansion high-temperature resistant insulation board.

11. The preparation method according to claim 10, characterized in that: The molding pressure is 3-50 MPa.

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